The Truth about Gasoline

[GMMerlin]

Here is some great information about gasoline
The truth about Gasoline
Click on the link at the bottom.

Here is part of it.
A number of myths about octane have grown over the
years. There is a widespread perception that the greater the
octane the better the performance. However, once enough
octane is supplied to prevent engine knock, there is little, if
any, performance improvement. One exception to this would
be in vehicles equipped with knock sensors. In these vehicles,
if octane is insufficient, the computer will retard the timing to
limit engine knock. If the vehicle is operating in the “knock
limiting” mode (retarded timing), using a higher octane fuel will
allow timing to be advanced, resulting in some level of
performance increase. However, even in these vehicles,
tests have shown that there is no perceptible performance
improvement from using a fuel of higher octane than that
recommended by the vehicle manufacturer.
Another myth is that using a higher octane fuel will result
in improved fuel economy (increased miles per gallon). Octane
is nothing more than a measure of anti-knock quality.
Fuel economy is determined by a number of variables including
the energy content of the fuel. Some premium grades of
fuel may contain components which increase energy content.
In those cases, fuel economy may improve slightly as a result
of higher energy content, but not as a result of the higher
octane. Two fuels of identical octane could have different
energy content due to compositional differences.
Consumers need only use a gasoline meeting the
vehicle manufacturer’s recommended octane levels. If engine
knocking occurs on such fuels and mechanical causes
have been eliminated, then the consumer should purchase
the next highest octane gasoline (above the manufacturer's
recommendation in the owners manual) that will provide
knock-free operation.

[twomorestrokes]

This s excellent and accurate information! There are a lot of folks throwing their money away thinking that they're doing their engine a favor.

[silverado122775]

I have never put in High Octane gas into my vehicles. My reason is that High Octane is designed for High Performance vehicles. Hence why Manufactures will put high grade Octane recommendations for high performance cars ie: camaro, GTO. Vette, Viper, etc...

All of my vehicles have lasted over 100K with no issues using low octane gas. Another thing I stick to sticking to the same gas company or staying with similar gas companies.

The other thing I stay away from are additives. Those to me are a big no no in my book. I beleive that if you stick with the same gas and the same octane you will not need additives to regain your performance.

Just my thoughts

[Bobby56]

I have the 2000 Silverado with the 5.3. I've noticed more pinging lately, which is lessened by using the mid-range fuel, 89 octane around here. I'm told this is all controlled by the computer. Why did I need to go to a higher octane?

[silverado122775]

Originally Posted by Bobby56

I have the 2000 Silverado with the 5.3. I've noticed more pinging lately, which is lessened by using the mid-range fuel, 89 octane around here. I'm told this is all controlled by the computer. Why did I need to go to a higher octane?

You may need have a diagnostics ran on your truck to see what codes are spitting out.

When do you notice the pinging? Engine cold or hot?

[firedawg81]

My 1999 Silverado Knocks for about 45 Seconds when i first start it cold in the morning. Is this pretty normal for that year?

[twomorestrokes]

Originally Posted by firedawg81

My 1999 Silverado Knocks for about 45 Seconds when i first start it cold in the morning. Is this pretty normal for that year?

If yours quiets down in only 45 seconds, hang onto it. You've got a good one.

[silverado122775]

Originally Posted by firedawg81

My 1999 Silverado Knocks for about 45 Seconds when i first start it cold in the morning. Is this pretty normal for that year?

Yes, it is very normal.. what you are hearing are the rockers and pistons rubbing against medal. It takes about 30-45 secs to get oil pumped to it when the engine is cold.

[Buzzkill1]

My 1999 Silverado Knocks for about 45 Seconds when i first start it cold in the morning. Is this pretty normal for that year?

I had the same problem and switched to shell gas vice the Top Tier Gasoline and it went away. Try it......I was a disbeliever and so was the Kwik Trip guy who had the same problem that now uses Shell lol.....It's the cleaner that's in it, it cleans out the carbon between rings.

[obbop]

Another way of looking at the issue.

Higher octane..... gas burns slower.

Lower octane......gas burns faster.

Faster burning gas gives more push against the piston.

Some engines, such as those with lots of compression, need a slower burning gas.

It is likely your engine does not need slower burning gas.

[internic]

actually i am pretty sure high octane gas burns hotter, meaning higher compression engines need it so the heat the air generates when it gets compressed does not pre-ignite the charge in the cylinder.

[twomorestrokes]

If anything it burns cooler, although I don't think that is stating things correctly. The actual temperature of the burning fuel really has nothing to do with it. High octane fuel has a higher flash point meaning it is harder to ignite, lessening the chance of pre-ignition. Hot spots in the combustion chamber are less likely to ignite the mixture prematurely.

[sub006]

In college (35 years ago) I was putting Super Shell 100 octane in my '64 Corvette. I tried a tank of Chevron Custom Supreme (103 octane) when it came out. The 327 would burn rubber with about half the throttle opening required with Shell.

Adjusting my right foot to give the same easygoing, everyday performance I had been getting before, my mileage was still off by about 10%. I switched back to 100 octane; wasn't going to pay more to get less mpg!

In my wife's newer BMWs a computer adjusts the engine settings based on the fuel used. Same story: 87 octane gives better mileage than 91.

[ktisdale_2]

Originally Posted by silverado122775

The other thing I stay away from are additives. Those to me are a big no no in my book. I beleive that if you stick with the same gas and the same octane you will not need additives to regain your performance.

As having multiple family members, friends, and having worked offshore myself, i know additives are usually a plus. All gasolines have additives, but the amount that each has is varied. The companies additives are added to enhance the performance of their product. Shell for instance puts detergents in their gas which would have no negative effects (not really sure on the upside is to them though).
I can not say to what extent they enhance them or how many are actually needed. But the majority of them, to my knowledge, have no adverse effects on vehicle performance.

HiSpeed

[wrparks]

I'm pretty sure the additives he is talking about here are the ones you can get at autozone and come in a bottle to add when filling up the tank. I hope anyway.