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Does it do ANY good to use STP (Oil Additives) ?

04-25-2008, 04:08 PM
When my Metro (The Phoenix) had worn rings, I used "STP" in the oil.

Now that I have about 20,000 miles on my new rings, the oil is just starting
to darken by 3,000 miles.

The rings are wearing....

My question is -

Is there any point to my adding STP to my oil?

From what I understand, STP keeps some lubrication on the rings and cylinder walls
after the engine has set for a while and all the oil drains to the sump.

Is that all it does?

I would like someone who KNOWS to respond - opinions I don't need.

As Dirty Harry said, "Opinions are like ___holes, every body has one and I don't
particularly want to see yours!"

Not to be one myself (I can't help it, I am one!), but I sure would like to know
if I am wasting my time and money adding STP to my oil....

I add STP to all my high mileage vehicle's oil hoping that I am doing some good,
but I really wonder.

I used to add 8 ounces of Transmission Fluid to my oil as a "detergent" because
many older engine mechanics vehemently (zealously) advocated doing so.

Just thought I would ask....


04-26-2008, 04:28 AM
I'm going to run around showing my opinion here, but it's all I've got, I'm not an oil expert. I wouldn't add anything to any fluid in the car except a bottle of fuel injector cleaner every 30K. The manufacturers spend billions coming up with the right combination of additives, and the car manufacturers and SAE approve them. Additives like STP and Lucas just make the oil thicker, now it's not 5W-30 anymore. Your oil is going to get dark, doesn't hurt a thing. Use good oil and a good filter and don't worry about it.

04-26-2008, 08:05 AM
Way more than you ever wanted to know about oil & additives:

GM Line Rat
04-26-2008, 08:13 AM
+1 on the additives (What Woodie said).......Read THIS ( article Doc, then hit the "Bobs The Oil Guy (" home page and their forums for all the answers you'll need on Oils, filters flushes etc... I Use Standard "Dino Oil" and AC-Delco filters in my cars. Then once every 50K Miles, they get the "Auto-RX" Engine cleansing treatment-------Thats it! It's frequently disscussed on their forums (Link ( or on the Auto RX Home Page (

04-27-2008, 10:50 AM
This "opinion" is not to comment on the oil additive issue, but to add that the darkening of the oil is a result of more factors than just worn rings...It's true that the oil gets dark due to exhaust gases leaking from the combustion chamber to the engine crankcase, a condtion called "blowby" and it's a result of bad rings, worn pistons and the cylinder being out or roundness and improper lubrication. Every car will have some blowby as pistons and rings expand and contratct due to heat variations meaning that when the car is cold you don't have as good of a seal as when you are at operating temps. I wouldn't worry about my rings unless the car is burnig rediculous amounts of oil, cause with bad rings you will be pumping oil to the combustion chamber and evidence of that is blue smoke in the exhaust (ican never memorize the exhaust colors), I SAID BLACK EARLIER.

04-27-2008, 11:00 AM
Wouldn't oil being burnt in the combustion chamber be blue smoke. Black smoke if from running rich...

Johnny Mullet
04-27-2008, 12:25 PM
Additives are a waste of money. This is not an opinion, but experience! I have gone through losts of cars and trucks. I have a primary vehicle that I keep, but don't drive a lot anymore. It's a 1995 Chevy 4X4. I got it with 35,000 miles and it has 130,000 after 5 years. I change the oil every 3-5k and use nothing but Baldwin Filters and regular Shell petrolium 5W30 oil. This truck vever gets any additives. I had to change the intake gaskets last year and I decided to but a new water pump, timing cover, etc on it. The engine was clean inside and I never had had issues with it.

I have also gone through a lot of beater cars and I never blew one up or had internal engine problems with them. I end up getting rid of them when they rust out in the frame or other critical areas. I have driven every one of them to the junkyard when it was time. Here is a list of my beaters and the approxomite miles on them when I got rid of them.............

1979 Chevy Impala Wagon 350 V8 - 110,000 miles (rusted away)
1975 Pontiac Firebird 350 V8 - 120,000 miles (junked due to rot)
1978 Dodge Aspen 318 V8 - 80,000 miles (traded for van below)
1973 Dodge "hippy" van 360 V8 - 210,000 miles (junked due to rot)
1977 Chrysler Cordoba 400 V8 - 90,000 miles (horrible crash! She saved my life)
1974 Plymouth Duster Slant 6 - 150,000 miles (rotted away)
1980 Chevy Monte Carlo 350 V8 - 100,000 miles (rear frame rot)
1984 Nissan Maxima 6 cyl - 370,000 miles (rear frame rot)
1990 Buick Park Ave 3800 V6 - 220,000 miles (subframe rot)
1994 Ford Tempo 2.3L 4 Cyl - 130,000 miles (huge deer obliterated this car)
1984 Pontiac Fiero 2.5L 4 cyl - 185,000 miles (fire in heater box)
1997 Dodge Ram 1500 318 V8 - 90,000 miles (2 trannys and front end issues, traded for Chevy Truck I have now)
1992 Mercury Capri XR2 1.8L 4cyl - 70,000 miles (rotted away)
1990 Buick Lesabre 3800 V6 - 239,000 miles (subframe rot)

Every one of these beaters had 3-5K oil changes with no smoke or engine issues and I never poured anything down the oil fill except motor oil. I put a huge amount of miles on my beaters since I enjoy driving and for the better part of my life, I have driven 100+ daily miles for work until recently when I got a job 15 miles from home.

I now have my Chevy Truck and my Chevy Metro. Hoping the Metro is good to me since this is the first beater I got that already had engine issues, but I feel it was worth fixing up.

04-27-2008, 06:20 PM
I just changed my oil today at 3,000 miles.

I usually add one of those silver cans of oil additive to it, but I didn't this time. I used the high mileage castro 5w-30 in it. Been using that for around 2 years, and the car has 180,000 miles, so I'd like to treat it nice, it is still running well in my opinion. I think I have a oil leak at the oil pan gasket, because I find I have to add a quart about every 2,500 miles.

I do use the STP Fuel Injector cleaner (black bottle) every oil change. Is this really necessary?

Johnny Mullet
04-27-2008, 06:26 PM
Fuel additives will contribute to fuel pump issues in my opinion.

GM Line Rat
04-28-2008, 07:33 AM
I have also gone through a lot of beater cars and I never blew one up or had internal engine problems with them. I end up getting rid of them when they rust out in the frame or other critical areas.
Damn Mullet! With a list of "Rusted Out" cars like that, it would appear you live in an area where they use alot of Road Salt during the Winter? Better keep a close eye on your Metro's Sub frame and wash the under body frequently during the Winter--------They rust out in the control arm / underbody area faster then any other car i've ever seen due to road salt rot! :shakehead I Used to live in Mich, moved down south 15 Years ago to the land of "No Road Salt use". My 94 Metro and My 91 Buick Century beaters are Spotless due to rust. My 95 Caprice is a "Garage Queen". We also have a 84 Chevy 4X4 Truck, just starting to surface rust around the cab corners----> time to fix that!

04-28-2008, 09:58 AM
I think that I have this rust on my control arm. I live in Baltimore, MD, and they use too much damn salt on the roads in the winter. I washed out the underbody when the weather turned nice, but I'd like to know how to control this rust.

Johnny Mullet
04-28-2008, 11:26 AM
To control the rust, get a gallon of used motor oil and mix it 50/50 with mineral spirits. Get a pumper (like for spraying weed killer) and spray the entire undercarriage except the exhaust and engine belts. Do this every year before winter.

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