What is the expert, scientific opinion of STP Engine Oil Treatment? When I was a kid, everybody used it. Now that I’m old and cynical, I suspect it’s just a way to get people’s money.
Edit: The title should’ve been all caps. I forgot that the server doesn’t understand acronyms.
This test seems valid; STP didn’t appear to do anything except increase the cold weather viscosity of multiweight oil, which is a bad thing.
I was hoping for a Stone Temple Pilots thread. 
When I was a yong motor-head in SoCal in the 70s, STP was well-known to be junk popular only with WW-II era guys from the South. Lotsa people put the stickers on their cars, but nobody who knew anything (or thought they did) put the stuff in their oil.
Perhaps STP’s popularity is regional. I bet the hard-core pickup-truck-n-double-wide NASCAR set still loves it.
If you were a kid in the 1960s the red oval STP stickers were the coolest thing to have on your notebook, bar none, partly because they were hard to get.
That’s all I got.
Old wore out big block engines in the 60’s in the hot summer time… Kept the lifters from rattlin. I did not think to use 70wt motorcycle oil :smack:
STP oil treatment, and similar stuff, has viscosity increasers (which might be good if your engine is nearly worn out) and film strength improvers (which, in the famous demonstration, make it impossible to hold on to a screwdriver.) Remember, though, every motor oil maker already includes every additive that makes oil work better.
Fixed title.