roadfrog

cheap.....

I'm surprised this post hasn't generated more of a can of worms! This is a most passionate subject for many folks.....

In 27 years of driving all kinds of vehicles for hundreds of thousands of miles, I've never had to tear down an engine. As long as it meets specs for your engine, you're good to go. Well, my .02 cents anyway.

I use 10-30 for my 'stang.

67mustang302

Some/most newer oils are starting to suck. They're removing the ZDDP package from all the new oils to meet ILSAC GF-4 standards, which the EPA requires has less than 800ppm of phosphorus, to protect catalytic converters. The problem is that by getting rid of the ZDDP to lower phosphorus levels, friction resistance in the oil drops dramatically. I just lost my main thrust bearing because of this(nothing else was to blame, don't ride the clutch, TOB and crank thrust were properly set, never lost oil pressure etc). Main thrust failure and some valvetrain failure is actually starting to become more common in engines running oils with lower zinc/phosphorus levels. I've never had any problem with Castrol before, and that's what I was running on this engine. The problem is they're ALL less than 800ppm of phosphorus if they're API GF-4, SM. Mobil 1 15-50 for racing, and Valvoline VR1/Racing are listed as not for street use, for racing use only. They have ZDDP in them. The Mobil and Valvoline oils with ZDDP are still API rated SM, but they're not GF-4. Best bet is to run an oil that's NOT API GF-4 and has higher zinc/phosphorus levels.