Doug,

I have read that some of the newer oils have less high pressure additives to improve converter life.

It might be that a older engine oil with more EP additives would work better. Also a 10-40 may get you a bit more film strength.

I ahve been running the 5w-40 wt Mobil 1 truck oil with good results.

www.bobistheoilguy.com has good info.

Kevin

87 Turbo Intercooled Raider, roller cam, torsen rear diff, LSD front diff, lockup auto with modified converter, V6 brakes, low transfer case gears...