STP Blue

[oilum]

I know I'll probably get a lot of ---- for this question, but I've never really got a definative answer on this.
For years I've thrown in half a bottle of the thick STP oil treatment when the oil has a few miles on it and I want to bring it back to life. This really seems to have worked well. When the 10w30 oil has about 2K on it it feels a little played out - just not quite as good as it did when new and adding half a bottle of the STP has made it feel as good or better than origianl for the last 1K miles before the oil change. I only do this spring/summer/fall and all my motors looks really clean inside and last a few hundred thousand miles just fine.
Guess the unanswered question is, does this stuff really attribute to sludge or any sticking ring issues?
Thanks

 

[Tempest]

Define oil "feeling good".

 

[oilum]

I sort of did, but what the addition of the STP does is return the oil to the reduced friction smoothness similar to what you have when the oil is brand new. I'd have to say it actually is a lot smoother and quieter and feels like the reduced friction is resulting in more engine HP / output. Petro oil feels like it suffers a breakdown in viscosity after just a few thousand miles and the STP feels like it improves or restores the viscosity.

 

[Tempest]

I suggest that you do a search on "viscosity index improver" on this site and do a little reading. I think you will find it very informative since that is mostly what STP is.

 

[Panzerman]

My dad put STP in everything, engines, rearends,transmissions, lawn mowers etc.. and swore by it. I always thought it was a waste of money even at a young age, but we never had any problems with it. He would let the engine warm up, then dump it in as it was running, it actually did sound like it got quieter as it worked its way in. I always wondered if it just ended up at the bottom of the pan after the first night, but I never drained out any goo, so I guess it mixed in.

 

[Shannow]

The big turbines at work need to have "jacking oil" (2500psi) to lift the shaft to allow the shaft to be turned.

During maintenance, a bottle of STP is run over each bearing, which allows it to slide fairly easily.

Doesn't mean squat for any other application, but it works there.

BTW, I spent 6 or 7 years running 20w50 conventional (Castrol GTX or Valvoline XLD) with a blue bottle of STP to make it a little more "robust".

 

[Oldmoparguy1]

For many years my standard engine assembly lube was a ~50/50 mix of any brand 20/50 oil and STP. In later years I added a lump of MolyCote, well stirred with a clean screw driver of course.

 

[Lost1]

I know a lot of folks who have used it over the years and most who do swear by it. It makes an excellent engine assembly lube- especially with some moly mixed in.
I've used it numerous times on engines that were basically worn out and had good results in extending engine life. It has been my experience that two bottles of STP and 5 quarts of 20W-50 can get you another 25,000 miles (or more) out of an engine that has worn rings, rods knocking, etc.
It's a bandaid, but when you're lacking funds for an overhaul it can buy you some time.

You say you've been using it for years with great results, so I'd say keep using it.

 

[TallPaul]

If you want to keep using STP, go with the red 4-cylinder bottle. Same basic stuff, but not as thick. There is a VOA of the red on this side. IIRC, was about 1700 ppm zinc and phosphorus and about 100 cSt at 100C.

 

[Crashbox]

I once used two bottles of STP Oil Treatment along with (IIRC) some 20-50 weight oil to help assist my old, tired (but free) slant six Dart through the emissions test. Don't know if it helped but that car passed the test with flying colors!