Other than that video, their product description says nothing about putting the stuff in the crankcase: Motor Treatment by STP® | Multipurpose Motor Treatment
Basically, it comes across as a fuel additive, and oh yeah, you can put it in your oil too. Poor copy writing considering it's supposed to be geared toward the gearheads!
Still, I'd prefer using something that has the viscosity of oil instead of water in my engine.

 

I agree the STP has not advertised the product well. The only other thing I found on their site is they has a list of which fuel additive to use and the mutipurpose one is not listed as a fuel additive.

When I use seafoam I do not drive the car. I install it let them idle for 25-30 minutes then put in addtive free oil. If the engine is really dirty I will install cheap clean oil and a cheap filter and do the same thing. In the end I am driving on No additive Mobil one and a good filter. I am thinking of the STP as a direct replacment for the seafoam but I have not tried it yet.

I am sure driving the car around the block would not hurt anything with the additive but I would not put the car in a situation it may need to be run hard with additives. I know a engineer that worked on mobil one test lab. They want no additives in their oil. If there was something they could add to there oil to make it better they would. Unwanted chemical reactions with additives is common and a problem.

When I mention my procedure to my friend at Mobil one he said just use Mobil one from the start and keep your PVC system maintained you will not need to clean anything. Classic answer.

 

I agree, that's why I use Mobil 1. What gets me, and part of it is buying into advertising, is the notion that you need to make an oil (synthetic) that's been formulated to be far superior to conventional oil, and put in an additive to make it perform (supposedly) "better". Yes, you are messing with altering the intended formulations. As using something as a "quick shot", like you described about taking it around the block, then change oil again, I don't see a problem with that.
There is a site; "Bob is the oil guy" that did a visual test with the Lucas oil stabilizer, using one of those gear driven displays that shows how the additive climbs the gears, where conventional oil didn't. Problem though, when they added it to the oil, and sped up the gears to simulate engine speed, the oil/additive mixture aerated itself. The oil turned tan in color due to it being full of air. The straight oil didn't do that. Sure scared me away from wanting to use the stuff. The website has since changed hands, and that demo is no longer there. If I find something archived I'll post it.

 

I saw that video but I found it hard to believe. We tried it at work because we had one of those demos and used a electric drill to simulate engine speeds better. We didn't have the same results as them, but I couldn't really tell anything noticeably different between them either. I wish I would have taken a video when we did it. But I'll see if we still have the display when I go into work tomorrow....I think our formal CCP stole it when he got fired. If so, I'll buy one and try it again.

STP also makes a oil specific additive I've used a few times with no trouble.
Oil Treatment by STP® | Protect Against Engine Wear

STP Multi-purpose product can be used in oil, 1 pint/5 quarts. Run at idle for 15 minutes. I'm cheating though and have a can in front of me. SeaFoam does all the same things, except states 1 pint is good for 10 quarts of oil and says it can be used through vacuum lines. STP doesn't state that on their bottles.

 

BTW I saw the STP video on this site. I assume they are a site supporter. I searched the site but I can not find the post it was in.

 

 

Thanks Slick. I still saw air bubbles in the plain oil, but the one with Lucas definitely looked frothier.