Am I Imagining Things

Am I Imagining things

I decided to fill-up my 99 3.8 Intrigue with premium fuel and the engine seems to be much stronger. I believe I can feel a real difference. What do you think am I imagining things and wasting my money on filling-up with premium fuel.

Waste of money, relatively low compression engine designed for 87 0ctane, in stock form

My info says if the owner's manual says to use regular, then your wasting your money buying premium.

If your vehicle knocked or pinged using regular, switching to premium should help. If the knock sensor detected a knock, it should retard the timing a little, if it is retarded too much, you would notice a performance issue. I can't say that the difference you feel is a timing issue, I don't know.

There is a higher detergent gasoline, called " top tier gasoline ", they say it will help performance, supposed to clean injector and intake valve deposits, better than the other gasolines. Gasoline is so high around here, I get the cheapest stuff I can find.

I have also noticed that premium fuel seems to run smoother. I do not think it is our imagination. I think it is related to the flame front being more controlled and less explosive and expanding more evenly with the premium fuel.

The only way to tell for sure would be to hook it up to a scantool and test it under similar circumstances with each grade of gasoline to see what sort of timing you were getting.

I switch between 87 and 89 quite often, because several stations around here offer 89 at the same price if not cheaper than 87 because its 10% ethanol, and that little bump in octane seems to make no difference to me.

There was previously a thread that discussed this issue. I know that the Northstar engine senses if knocking occurs and retards the timing automatically. Different years of the Intrigue recommend either regular or mid-grade. The best reason to buy premium gas is to get extra additives that prevent carbon build-up. For tier-one gas, premium usually has 5 times the additives that regular has.

People who buy no-name gas from Mom and Pop stores to save a few pennies short-change themselves because usually the gas doesn't have very much (if any) additives in it.

People who buy no-name gas from Mom and Pop stores to save a few pennies short-change themselves because usually the gas doesn't have very much (if any) additives in it.
Not necessarily. Around here the smaller, independent gas stations purchase their fuel from an intermediate supplier,and it comes from"The Big Guys"(Mobil, Sunoco, Citgo), and it's the same gas as you'd get at the corporate branded stations.It's like buying a store brand product made from a national brand manufacturer, it just has a different label.

The reason i am buying premium these days is due to the fact that premium costs only 6 cents more per litre vs regular gas. Here in the Toronto area the Esso staion sells regular for $102.9, Mid-Range and Premium for the same price of $108.9, I asked the attendent why the mid range and premium are the same price he said they have an over supply of premium due to more people using regular in their cars. As long as premium is sold at that small price difference vs regular I will use premium the 3.8 is running better.

Not necessarily. Around here the smaller, independent gas stations purchase their fuel from an intermediate supplier,and it comes from"The Big Guys"(Mobil, Sunoco, Citgo), and it's the same gas as you'd get at the corporate branded stations.It's like buying a store brand product made from a national brand manufacturer, it just has a different label.

I agree that all the gasoline comes from the same refinery. However, prior to the tanker getting their load of gasoline, the driver adds the additive package. If you don't buy a tier-one gasoline you don't know what you are getting in terms of the additives. Out of the tier-one gasolines I would say that Chevron additives (Techron) are best followed by Shell V-power.

A study of independent gasoline stations shows that they sometimes don't even meet the federal standards for additives to prevent clogging of fuel injectors.

So, the bottom line is that it is worth spending a few pennies more for tier-one gasoline.

The reason i am buying premium these days is due to the fact that premium costs only 6 cents more per litre vs regular gas. Here in the Toronto area the Esso staion sells regular for $102.9, Mid-Range and Premium for the same price of $108.9, I asked the attendent why the mid range and premium are the same price he said they have an over supply of premium due to more people using regular in their cars. As long as premium is sold at that small price difference vs regular I will use premium the 3.8 is running better.

The primary reason premium has a higher octane rating is because the hydrocarbons in it have a longer chain than those in regular or mid-grade. The longer chain molecules burn cleaner and leave much fewer deposits on the valves and cylinders. Here in Oklahoma premium costs 20 cents more a gallon than regular.

Probably the reason the 3.8 is running better is because the gas has plenty of additives and its burns cleaner. Hence, the engine has more pep.

I agree that all the gasoline comes from the same refinery. However, prior to the tanker getting their load of gasoline, the driver adds the additive package. If you don't buy a tier-one gasoline you don't know what you are getting in terms of the additives. Out of the tier-one gasolines I would say that Chevron additives (Techron) are best followed by Shell V-power.

A study of independent gasoline stations shows that they sometimes don't even meet the federal standards for additives to prevent clogging of fuel injectors.

So, the bottom line is that it is worth spending a few pennies more for tier-one gasoline.

Great points you have made and they make sense. The last time I filled-up at a no name gas station was around 35 years ago. I filled up at a canadian tire gas station. After filling-up in exiting the gas station I had to make a left turn I nailed the gas pedal to avoid been hit by uncomming traffic it felt like I had my emergency brake on and I checked and it was "not" on that is how poorly my car ran after filling-up with a no name gas and I also got the worst milage. That was the last time I filled up with no name. Oh yes my car at the time was a 67 Cougar with a 289 auto. One other point I find that my 99 Intrigue doesn't seem to run as well on Sunoco regular gas. I find that it runs best with Esso

Yours doesn't run well on sunoco regular? I seem to have good gas mileage and normal performance with that. That being said, I always use BP/Amoco, as there are many of them conveniently located on my routes. Whenever I can, I use shell. Never will I use Getgo or Kwikfill or Sheetz. Back when gas dipped down to the low 2's, I started using premium for a little while and didn't really notice a difference. Just curious, someone mentioned that some intrigues require 89 octane. I thought they all only called for regular, no matter which engine. Can someone back my thought up?

Yours doesn't run well on sunoco regular? I seem to have good gas mileage and normal performance with that. That being said, I always use BP/Amoco, as there are many of them conveniently located on my routes. Whenever I can, I use shell. Never will I use Getgo or Kwikfill or Sheetz. Back when gas dipped down to the low 2's, I started using premium for a little while and didn't really notice a difference. Just curious, someone mentioned that some intrigues require 89 octane. I thought they all only called for regular, no matter which engine. Can someone back my thought up?

Mu understanding is that the '99 owners' manual recommends 87 octane, and the '00 manual recommends 89 octane. The GM Helms service manual recommends premium.

Rolm: I have no doubts that your engine did feel stronger. This winter i had a few misfires which I attribute to the gas line antifreeze I added (HEET, I believe). I added a couple of bottles of Chevron Techron to clear up the lines (it was suggested by someone in another forum). I swear my engine felt stronger and it did help clean up the fuel. But I did not experience better gas mileage (I keep a notebook in my car to track mpg). If your Intrigue runs fine on 87 octane, then using 93 is a waste of money. If it makes you feel better, use 93 for every fifth fill up.

Now having said that, I don't buy the "top tier" vs. "cheap gas" argument. I live in southcentral PA (not to be confused with southcentral LA). This area is dominated by Sheetz, Rutter's, Turkey Hill. You would be hard pressed to find Exxon, Mobil, Sunoco, Shell, etc. (Haven't seen a Chevron station in about a decade). In our area, there is one distributor for all the gas.

I need hard proof that a) the additional additives that Shell, Amoco, Chevron add to their fuel are necessary and b) this "cheap gas" is bad for fuel lines and engine. BTW, a definition of "cheap gas" would be nice. My 2000 Intrigue has 144k miles and the last 5 tanks have averaged 27.5 mpg. I have never cleaned the fuel injectors and the current fuel filter has been on for about 80k miles. I did some searching on the internet and haven't been able to find these answers. I found tons of articles on Top Tier gas but nothing that says it is necessary for the average car? If I had a BMW or Mercedes then yes I would fill up with 93 octane at Exxon all the time. Instead I have a 8 year old car with 144k miles on it. I'll fill with the cheapest gas I can find and save my money for other things.

Rolm: I have no doubts that your engine did feel stronger. This winter i had a few misfires which I attribute to the gas line antifreeze I added (HEET, I believe). I added a couple of bottles of Chevron Techron to clear up the lines (it was suggested by someone in another forum). I swear my engine felt stronger and it did help clean up the fuel. But I did not experience better gas mileage (I keep a notebook in my car to track mpg). If your Intrigue runs fine on 87 octane, then using 93 is a waste of money. If it makes you feel better, use 93 for every fifth fill up.

Now having said that, I don't buy the "top tier" vs. "cheap gas" argument. I live in southcentral PA (not to be confused with southcentral LA). This area is dominated by Sheetz, Rutter's, Turkey Hill. You would be hard pressed to find Exxon, Mobil, Sunoco, Shell, etc. (Haven't seen a Chevron station in about a decade). In our area, there is one distributor for all the gas.

I need hard proof that a) the additional additives that Shell, Amoco, Chevron add to their fuel are necessary and b) this "cheap gas" is bad for fuel lines and engine. BTW, a definition of "cheap gas" would be nice. My 2000 Intrigue has 144k miles and the last 5 tanks have averaged 27.5 mpg. I have never cleaned the fuel injectors and the current fuel filter has been on for about 80k miles. I did some searching on the internet and haven't been able to find these answers. I found tons of articles on Top Tier gas but nothing that says it is necessary for the average car? If I had a BMW or Mercedes then yes I would fill up with 93 octane at Exxon all the time. Instead I have a 8 year old car with 144k miles on it. I'll fill with the cheapest gas I can find and save my money for other things.

It sounds to me that the local brands you mentioned do a good of putting additives into their gasoline. Otherwise, I doubt that your Intrigue would be running as well as it is. You are also using after-market additives. Around Oklahoma area QT is a good brand of gasoline, rated Tier-one. You might want to find out what tier-one gasoline is all about. I have a friend with a '95 Blazer who just buys the cheapest gas he can find, the car runs very poorly, probably a blocked fuel injector(s).

Here are a link for you. There are others but they go to car forums which I'm not alllowed to post.

http://www.aa1car.com/library/bad_gas2.htm

Using your buddies poor running 13 year old Blazer to support your argument is not convincing. Not unless his car is in the same shape as when he drove it off the lot, I think it is safe to say there are too many variables.

I've read the articles (note multiple articles) on Top Tier gas which is why I dispute the claims. I find it interesting that brands like ExxonMobil, Citgo and Sunoco are not on this list. A major car manufacturer like Ford has not hopped on the band wagon. Top Tier gas is nothing but a marketing tool. I'm not disputing their claims that their additives do not work but are they necessary for my car to run at peak performance. Like I mentioned, if I owned a BMW or Mercedes, I would fill my car with top tier fuel. You buy these cars for a reason. We are talking about an Oldsmobile.

To make my question clearer is the gas that meets the minimum EPA standards not enough for my car? Or are there other factors? Again, what is this "cheap gas" that will clog my injector ports and cause deposits? Every "top tier" gas article mentions it, but if the base gasoline in an area is provided by the same distributor and that gas meets the EPA minimum standards, what is "cheap gas"? This is my confusion.

Here's an intersting article from USA TODAY from two weeks ago: http://www.usatoday.com/money/industries/energy/2007-06-13-bad-gas-usat_N.htm?csp=34

Cheap gas is defined as gasoline which only has the minimal EPA level of additives. Gasoline that has the minimal amount of additives is not good enough for the Intrigue if you want peak performance.The Northstar engine is a very high performance engine. There is no way in knowing how much additive you are getting in your gasoline unless it is a Tier-One gas. Tier-one gas is more than a marketing tool for the gasoline companies since the major car manufacturers (except Ford) pushed for more addtives. The fact that not all gasoline marketers have joined the tier-one program doesn't mean anything except that they know that the vast majority of Americans are ignorant about cars and gasoline.

I know that the additives work because I have driven cars using minimal additives for thousands of miles and then gone on a long run trip where I use Chevron gas. After about 5 tanks full I noticed a distinct improvement in performance. BTW, the Shell gas I ususally buy for a penny more a gallon as opposed to "cheap gas" is actually cheaper for me to buy since Shell gives me a 5% rebate, which at $3 a gallon is 15 cents. Hence, the tier-one gas is 14 cents cheaper. The best of both worlds.

So what you are saying is gas that meets the minimum EPA standards will clog my fuel lines and cause decrease performance??? And the proof of this is.....your testimony???? give me something to read, give me unbiased lab testing, give me something other then your "seat of the pants" experience. Quite honestly, my personal experience is I have driven cars for thousands of miles that are not Top Tier gas and have not had any fuel system problems. So which one of our opinions matters....neither which is why i am asking for unbiased lab reports, articles, etc.

I'm not trying to argue with you or belittle you. I value your opinion. I'm the type of person who does not believe claims until I see proof. What I have read so far tells me Top Tier gas is about marketing since no one has shown me that the additives in EPA minimum standards gas are not enough for the average car. Again, I'm not saying that the manufacturers of produce Top Tier gas are lying or even that their products don't do what they claim. I just don't believe the claims that "cheap gas" (any gas not branded Top Tier) will not allow your car to acieve peak performance (whatever that is). I view the word "cheap" as negative. If I had purchased a performance car (The Intrigue is not a performance car), then I would follow their recommendation. Holding up a clean piston versus a dirty one is not proof. Putting an exhibit showing two cars, one with Shell gas and the other with "cheap gas", and showing them running side by side doesn't cut with me. Reminds me of the nitrogen in your tires. Regular air is 78% nitrogen. The key thing is to check your tire pressure.

I guess the reason i get upset with this Top Tier gas claim is I view the work "cheap" as a negative. I have no Top Tier gas in my area or at least not in my normal daily travels. Nothing but cheap gas.

So what you are saying is gas that meets the minimum EPA standards will clog my fuel lines and cause decrease performance??? And the proof of this is.....your testimony???? give me something to read, give me unbiased lab testing, give me something other then your "seat of the pants" experience. Quite honestly, my personal experience is I have driven cars for thousands of miles that are not Top Tier gas and have not had any fuel system problems. So which one of our opinions matters....neither which is why i am asking for unbiased lab reports, articles, etc.

I'm not trying to argue with you or belittle you. I value your opinion. I'm the type of person who does not believe claims until I see proof. What I have read so far tells me Top Tier gas is about marketing since no one has shown me that the additives in EPA minimum standards gas are not enough for the average car. Again, I'm not saying that the manufacturers of produce Top Tier gas are lying or even that their products don't do what they claim. I just don't believe the claims that "cheap gas" (any gas not branded Top Tier) will not allow your car to acieve peak performance (whatever that is). I view the word "cheap" as negative. If I had purchased a performance car (The Intrigue is not a performance car), then I would follow their recommendation. Holding up a clean piston versus a dirty one is not proof. Putting an exhibit showing two cars, one with Shell gas and the other with "cheap gas", and showing them running side by side doesn't cut with me. Reminds me of the nitrogen in your tires. Regular air is 78% nitrogen. The key thing is to check your tire pressure.

I guess the reason i get upset with this Top Tier gas claim is I view the work "cheap" as a negative. I have no Top Tier gas in my area or at least not in my normal daily travels. Nothing but cheap gas.

First of all, I did not say that all gas that is not Top-Tier is "cheap gas". I defined "cheap gas" as any gasoline that has the minimal EPA additives. That is an important difference. I said that we just don't know what additives/amount is in gasoline that is not label top-tier.. Consequently, your personal testimony that you have driven a car for thousands of miles not using top-tier gasoline without fuel system problems does not prove anything since you don't know what additive or amount thereof were in the gas that you bought.

Secondly, I think that the Intrigue has a high-performance engine. Maybe we should have a poll on that question.

I think that if you re-read that article I posted it will show that the Federally mandated amount of additives may not sufficient for some cars. I will find some more information about the problems that unleaded fuel causes for fuel injectors before too long.

BTW, I have nitrogen in all tires of my 3 vehicles. It's the only way to go.

There are some more links:

http://www.sfrcorp.com/news/automakers-oil-industry-in-fuel-fight.php

http://www.toptiergas.com/deposit_control.html

That was the point of my example. My personal experieince means nothing in this argument just like your friend's 95 Blazer running bad is a sign of long use of bad fuel or your driving thousands of miles... I also drive 25k miles a year.

Thanks for the websites. Without looking at the one, I'm sure it was funded by the Top Tier group just by it's link.

We'll save the nitrogen debate for another post. Start a poll about the 3.5L being a performance engine. I'm interested in seeing the responses. You know what my answer will be.

Im not saying you cant benefit with this engine from using one brand of gasoline or another.

But as far as actually using a higher octane, meaning the higher the number, the harder it is to ignite, I dont think in this application is necessary.

Two things immediately pop in my mind when thinking about requirement of high octane gas. High compression engines, and forced induction. Both of which serve to create mass quantities of heat, making the fuel/air mix more likely to pre-ignite with a lower grade of gasoline.Also, neither of which apply to the Intrigue.

As maxwedge said in the very first reply, the 3.5 is a fairly low compression engine, and forced induction is obviously not an issue, and im having trouble believing that it creates enough heat otherwise to cause pre-ignition.

I think to call the 3.5 a performance engine is a bit of a stretch, it is a solid performer, and is a very well designed and more sophisticated engine. But I have a hard time saying that I have a performance engine when my car would run mid/high 15s at the fastest.

Again, Im not even touching the detergent debate, but unless you can hook up to a scantool and show me the timing differences between 87 and higher then im not a believer.

I think we need a definition of a "performance engine".

I think we need a definition of a "performance engine".



Not an easy thing to pin down, I agree, but I would say that it would be either an engine with a high compression ratio to get maximum hp per displacement. Or an engine with some form of forced induction attached to it. Or in some cases both.

I agree littlehoover. 87 octane is all you need for the Intrigue. The 3.5L is a nice engine but that's it. I think a performance engine also needs to be a leader in its class.

I was hoping you could join the detergent Top Tier debate. We need more participants.

Jimmy: Read the two websites and as expected both are biased. One is the top tier analysis and the other the guy has an advertisement for fuel additives at the bottom of the page. Still not convinced since it is not an industry wide standard and the entire initiative was started by BMW. They recognize those who put additional additives but their are others that do meet these standard but choose not to be a part of this group. So who do you believe? It makes me wonder if it is the quality of the gas (standards haven't changed since 1995) or are certain manufacturers fuel systems more sensitive then others? Hmmmmmmmmmmmmm.

I agree littlehoover. 87 octane is all you need for the Intrigue. The 3.5L is a nice engine but that's it. I think a performance engine also needs to be a leader in its class.

I was hoping you could join the detergent Top Tier debate. We need more participants.

Jimmy: Read the two websites and as expected both are biased. One is the top tier analysis and the other the guy has an advertisement for fuel additives at the bottom of the page. Still not convinced since it is not an industry wide standard and the entire initiative was started by BMW. They recognize those who put additional additives but their are others that do meet these standard but choose not to be a part of this group. So who do you believe? It makes me wonder if it is the quality of the gas (standards haven't changed since 1995) or are certain manufacturers fuel systems more sensitive then others? Hmmmmmmmmmmmmm.

dtown, the first link was a reprint from the Kansas City Star which I find hard to think of as bias.

I agree that regular grade gas is just fine for the Intrigue, and although the use of premium grade would add a little performance edge, most drivers would never drive their Intrigues to the point that it would matter.

I think that even those major gas marketers who don't belong to the Top Tier group, are adding more additives than the minimal amount required by the EPA.
The people who are probably selling the gasoline with the minimal amount are the smaller "Mom & POP" convienience stores or the smaller local chains.

Like I said earlier, fewer engine deposits means better engine performance. And, the higher the additive package in the gasoline, the cleaner the engine will be. Those are 2 facts that don't seem to be in dispute.

<<dtown, the first link was a reprint from the Kansas City Star which I find hard to think of as bias.>>

It was the link to the ad at the bottom of the page and the fact it was on the "Green" page. Still a good post. Like I mentioned you got me interseted in finding out if there is truth to their claims. You got me thinking.

I do agree that since BMW, Honda and Toyota raised this issue, the industry as a whole problably "policed" themselves and increased the additives. With the competition for gasoline so intense now, you can't afford to be label as having poor quality gasoline. Unfortunately we will never know.

<<Like I said earlier, fewer engine deposits means better engine performance. And, the higher the additive package in the gasoline, the cleaner the engine will be. Those are 2 facts that don't seem to be in dispute.>>

Never disputed this claim. My point is what additives are necessary to ensure performance of my car. Is it the EPA minimum? Is it 5 times the EPA minimum? Or is it somewhere in the middle? Which additives are the necessary one? how do I know which additives my local Sheetz or Rutter stores add on top of the EPA minimum? Do they add any at all? Who made BMW, toyota, Honda, Audi,etc the king of gasollne fuel quality? these are my questions.

I gues my frustration is the gas in my area is all priced within 5 cents of one another but we have no Top Tier gas stations. These gas stations qualify as your "small local chains" and "Mom & Pop convenience stores". Waht do I do? I guess i can't buy a BMW.

<<dtown, the first link was a reprint from the Kansas City Star which I find hard to think of as bias.>>

It was the link to the ad at the bottom of the page and the fact it was on the "Green" page. Still a good post. Like I mentioned you got me interseted in finding out if there is truth to their claims. You got me thinking.

I do agree that since BMW, Honda and Toyota raised this issue, the industry as a whole problably "policed" themselves and increased the additives. With the competition for gasoline so intense now, you can't afford to be label as having poor quality gasoline. Unfortunately we will never know.

<<Like I said earlier, fewer engine deposits means better engine performance. And, the higher the additive package in the gasoline, the cleaner the engine will be. Those are 2 facts that don't seem to be in dispute.>>

Never disputed this claim. My point is what additives are necessary to ensure performance of my car. Is it the EPA minimum? Is it 5 times the EPA minimum? Or is it somewhere in the middle? Which additives are the necessary one? how do I know which additives my local Sheetz or Rutter stores add on top of the EPA minimum? Do they add any at all? Who made BMW, toyota, Honda, Audi,etc the king of gasollne fuel quality? these are my questions.

I gues my frustration is the gas in my area is all priced within 5 cents of one another but we have no Top Tier gas stations. These gas stations qualify as your "small local chains" and "Mom & Pop convenience stores". Waht do I do? I guess i can't buy a BMW.

Doesn't seem like there is much for you to do at this except buy some Techron additive every 5000 miles or as needed. I guess you could email those local gasoline marketers in your area and ask them what additives they use and in what amount. Would be interesting to see what they say.

I'm just tickled pink that Shell moved into my area about 4 years ago. Now, I don't bother getting a "throttle body and fuel injector" cleaning at the local oil change place because I can't tell any difference in the car's performance after getting it done.

If you ever take a long road trip in your Intrigue, buy Chevron or Shell and I suspect you will see the difference in your car's performance after 5 or 6 tankfuls.

As much as I ma debating with you about this, I do follow some basic guidelines. Since price is normally not an issue in my area: 1) buy gas where convenient (during my normal travels); 2) frequent places that have a lot of business (high turnover of gas); 3) when traveling out of the area, buy name brand or a brand I am familar with.

I'll try e-mailing the local companies. See what kind of response I get.

Gentelman great debate. The bottom line is this, now that premium gas is only 6 cents a liter more here in the Toronto area. I use it at every fill-up and I added the same gas in my lawnmover and weed-wacker and in my leaf blower I had to pull at least 10 times to start the weed-wacker and the leaf blower with regular gas and it only takes 1 or 2 pulls with premium gas. I am sold I will use premium in my car and all other gas engines from this point on. Call me crazy but the proof is in the pudding.

Man oh man this 3.8 is running so nice on premium gas that I will never go back to regular again.

An update on my use of premium fuel, I noticed that my exhaust pipe has blackened vs when I was using regular fuel. When I used regular fuel the end of the exhaust pipe was clean, now I see that it has blakened. I have to assume this due to all of the extra cleaners in the premium fuel and it is cleaning the engine and the exhaust system. Any thoughts out there.

An update on my use of premium fuel, I noticed that my exhaust pipe has blackened vs when I was using regular fuel. When I used regular fuel the end of the exhaust pipe was clean, now I see that it has blakened. I have to assume this due to all of the extra cleaners in the premium fuel and it is cleaning the engine and the exhaust system. Any thoughts out there.

If that is the case, then I would assume that eventually the tailpipe will become clean again once all the deposits are removed. Keep an eye on it and let us know what develops down the road.

Jimmy

I can buy stp injector cleaner for a buck and use it on 2 tanks. does this give u the same thing as high dollar gas. it would be cheaper to add it myself with the high octane stuff 25 cents more a gallon.

The many so-called octane boosters boost the octane level by next to miniscule amounts, something like .1 point. I cant remember the exact number, but almost all of them are a waste of money. Either way it wouldnt raise your octane level enough to compare with buying premium gas. Which Im not convinced the 3.5 needs, and I know the 3.8 doesnt, but whateva.

I can buy stp injector cleaner for a buck and use it on 2 tanks. does this give u the same thing as high dollar gas. it would be cheaper to add it myself with the high octane stuff 25 cents more a gallon.


The really good detergents, like Techron, cost about $6 to treat 12 gallons. If you buy top-tier gasoline, regular grade, the cost is not that much more than other gasolines and there is no need to buy more additives. Gasolines that are significantly lower in price usually contain a lot of ethanol.

octane boosters and lead additives are a must is some conditions. Older engines can get real hot and get pre-ignition issues. Marvel Mystery oil is also used in aircraft engines to keep carbon off the valves of a hot engine. I swear by them.

Valves will start to stick with a build-up of carbon and heat. In a rotary- air-cooled aircraft engines the situation almost mandates their use.

For my 1966 440 Charger I will use the lead additives when it is warm +70-80 deg F. That engine runs hot and the pistons are large = detonation issues. +the timing adjustment is not automatic like the Intrigue. -and that is on premium gas (or whatever crap they sell as premium now).

Does the Intrigue need these additives? A little fuel injector cleaner ever 3 tank full may help. The aluminum block of the 3.5L dissipates heat well.