Does anyone have any thoughts on using oil addititves such as STP? I have added one bottle of the Walmart house brand version of STP, "SuperTech" oil addititve at every oip change. Oil is also Supertech. My 1999 Expy has 171K on it & runs great!
Thanks,
John

 

Unless you have blowby or worn rings, in a loose, high mileage engine, additives are completely unecessary. Especially STP, it serves no usefull purpose, except making an oil needlessly thick at startup, causing your oil pump to work much harder, as that thick oil sits in your oil pan. Meanwhile, your upper valve train is running nearly dry, with only film strength from the previous run, protecting moving parts that are getting hot, quick.

Modern engines today are built with much tighter tolerances, and emission controls, catalytic converters, ect. all rely on a modern oil. STP was built for engines back in the 60s and 70s, where oils broke down faster, and engines tended to have larger internal passages. Hence, STP was a popular additive.

Today however, you are serving no pupose by using it, really.

 

I would take that STP out of there and see if you notice an improvement just by getting rid of it.

Mike

 

[QUOTE=Ed;6053406]Unless you have blowby or worn rings, in a loose, high mileage engine, additives are completely unecessary. Especially STP, it serves no usefull purpose, except making an oil needlessly thick at startup, causing your oil pump to work much harder, as that thick oil sits in your oil pan. Meanwhile, your upper valve train is running nearly dry, with only film strength from the previous run, protecting moving parts that are getting hot, quick.

Modern engines today are built with much tighter tolerances, and emission controls, catalytic converters, ect. all rely on a modern oil. STP was built for engines back in the 60s and 70s, where oils broke down faster, and engines tended to have larger internal passages. Hence, STP was a popular additive.

Today however, you are serving no pupose by using it, really.
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Plus, in the 60s and 70s, cars were built with carburators. These cars especially when older, tended to have chokes that stuck closed, opened slowly, and excess gasoline tended to thin and dilute the oil over time.

STP was used with the thinking it would help coat engine parts better, thus helping out the oil being diluted with small amounts of raw gasoline.

So you can see, modern fuel injected engines, is completely unecessary, because unless you have a faulty injector, you don't suffer oil diluting from gasoline at shutdown / startup/.

STP still sells because people who don't know, find old habits hard to break. It's like the person who still pumps the gas pedal when starting their 2007 Buick LaCrosse -- all because they pumped the gas in their '64 Buick, so the 2007 models also must need this...

 

It is especially hard to break the habit if you have used STP like I have at every oil change & the vehicle has 171K on it & runs great. Whether the STP has actually done anything positive...well, who knows...but I'm kinda afraid to stop using it since I have experienced good engine longevity using it.
I am curious though...does STP actually seperate from the engine oil when the engine is turned off or does it blend in with the oil? Does adding STP to 5W - 20W oil change the oil viscosity to say 5W - 30W?
Thanks,
John

 

You can click here: The Clorox Company MSDS - Material Safety Data Sheets

to find the STP Oil Additive MSDS.

It is:
60%-100% Mineral Oil
10%-30% Petroleum Distillates (probably kerosene of similar)
1%-5% Zinc Compounds (ZDDP I'd guess)

Is it hurting? Your mileage seems to indicate not likely.
Is it helping? My guess would be no.

170,000 miles is really not that high these days.

 

STP= stop that Preformance

 

I agree with "Ed". Adding the STP is like adding some straight 50 weight oil to the crankcase. You are now using a thicker oil. Much harder to pump around when cold. The danger is that the STP could end up masking some serious engine problems that need attention. In my opinion it's a band-aid. Todays modern oils are all you need. Save the money you are using on STP and buy good quality oil. If you really need the STP give me a call, I'll sell you some pills to make you bigger, harder, last longer, grow hair on your head, and lose 10 pounds. All in 2 short weeks!

 

Well said, Tuckerjw. That is it in a nutshell. I mean STP is not going to cause an engine not to start, or blowup, overheat ect. However, it does alter the balance of any quality motor oil, and a quality motor oil in the correct viscosity is all any tight, normal engine needs.

I mean, I could also run my tires with 15 PSI of air pressure. They won't blowout, but it's not what the tire manyfacturer calls for, and this low pressure also is causing other problems -- namely increased rolling reisitence, heat buildup, and extra gasoline useage /waste. Plus handling, ride, load, all is comprimised, same with STP you're introducing comprimise into an already known factor with SAE rated oil with the starburst emblem.

Same with STP, and similar additives. Worn out engines need this oil film "cushion", but a tight engine does not. Pure oil is all that is necessary. Plus, it's ALL manufacturers that say that. It's not like GM says "no", but Ford, Chrysler, BMW, Porsche say: 'we recommend STP in our engines'. No manufacturers say that, and for good reason.

MEMO to JohnKirk: I am sure your vehicle could easily have attained 171K without STP, other engines do this. It's more along the factors of modern oils, and how they are made. STP, I'm sure, had very little to do with you making it to this mileage. A hard habit to break, that's true. I used STP in the 70s when i was a teenager. However, once I realized what it was and why my engines did not need it, I discontinued use of it decades ago. Same with Slick 50. Prolong. DuraLube. TufOil ...On and on...