sallyman1

Once in a while I add STP to my gasoline car (401000km ) on it. Has any1 ever added a bit of STP to their 15w40 in a diesel pickup?

gunny

Engine oil goes in the crankcase.

Gear oil goes in the differentials

Diesel fuel goes in the fuel tank (a little bio sometimes)

Antifreeze goes into the cooling system.

Do not use additives unless you are addressing a particular issue or problem.

sallyman1

STP is oil? why do some add 2 cycle oil to their fuel? that should go in crankcase then?

bluebull

Actually STP has alot of anti-wear additives in it, the same as most oil companies use. Most oil companies don't use as much of the additives anymore because of the catylitic converter could be damaged by the additives. STP has excellent anti-wear additives in it and if it wasn't for my cat I would be using it.

Strjock81

2 cycle oil is meant to be burned in the fuel.

You will gain absolutely nothing by adding STP to your oil, but in small amounts it probably won't hurt anything either. All it is is a superthick brightstock base oil with some Viscosity Index Improvers and a small dose of the antiwear additive, ZDDP, which is already found in high doses in diesel engine oil.

One thing that would concern me is if you live in a cold climate don't use much of this, particularly in dino oil, as it can make it so thick it will be hard to pump the oil when you start it up early in the AM.

gmctd

Shell Rotella CH-4+ had that peculiar odor because of the enhanced zddp content - unfortunately the CJ oils are reduced sulphur blends - the thio in zddp is sulphur, so it has been reduced - CH\CI was the last 'good' oil

The blue stp has viscosity enhancers, which you do not want in your Diesel oil, as mentioned, due to increased starting load

If you can find the red stp, for small oriental vehicles with 4cyl engines, it has same quantity zddp as the blue bottle, but lowered viscosity improver for those anemic jobs.

You do not want to add that stuff to the '07 engines, due to the multi-stage catalyst sysetm - sulphur will damage those in short order.

And, goes without saying, here - stp is for the crankcase, or even a noisy manual tranmission, but not for the fuel tank.

Spooler

Don't put STP in your oil. No need for it at all. Just use quality oil designed for a diesel. That stuff is like serious artery clogging slugg building stuff in my opinion. I have used it before and those were my results and that was years ago.

gmctd

Sure you're not thinking the moly additives?

Did a good job as long as the engine was running - 1st time you shut it down, the moly precipitated outta the oil, layed along the bottom of the galleries - more and more each shutdown till no more moly in solution - hadta strip the engine, flush out the galleries with hi-pressure solvent to restore operation.