I'd stay away from anything that says it's GL4/5 compatible. I put that stuff in my transmission and had to replace the transmission less than 6 months after that. If it says GL-4, find something that only says GL-4. Redline and AmsOil are both good. I run Redline in mine now. Nice smooth shifts with no problems.

I got mine from Amazon.com for just under $16/quart.

 

So I should go with Redline? It would be my best bet? What do y'all think about royal purple oil wise? Overrated or not?

 

Do y'all run the Redline in the diffs and transfer case same as the transmission. I know this may be a dumb question but just trying to figure it all out.

 

no, read the FSM for specifics for each item if you want to stay factory. I run the heavy shock proof for the diffs because it keeps the lockers from being loud and obnoxious. I run the MT90 in the transmission and the standard recommended weights from the FSM in the t-case.
I dislike royal purple for two reasons. The rep that came around the shop I worked at, was the most annoying SOB I ever met and their oil is purple and looks dirty right out of the bottle due to the purple dye… makes it harder to tell when it's ready for a change...

 

look at the context of the advice, the emphasis is on running dino fluid for the break-in period, not synthetics.

i'd guess that all of the gl-5's on the market today will not hurt the yellow metals in our transmissions, assuming that we even have any... wrt the cheap warren unilube coastal stuff that i'm running for break-in:

http://www.tractorbynet.com/forums/c...ar-oil-gl.html

the redline lube will be a definite improvement over that coastal gear oil... here is a lab report on the motorcraft fluid that i'm going to run, in terms of wear, it doesn't get much better than this:

"My OSA...
2 Full track days and probably about 30 autocrosses over the course of a year. I spent a lot of time on the rev limiter, so that combined with the track miles is why I changed it out 'early'. Looks ok?"


http://forum.miata.net/vb/showthread...270393&page=29

 

Thanks for posting a blackstone report. I do them pretty regularly with the motor oil in my E36, but haven't done the transmission or diff yet.

 

Have decided to go with redline mt90 and am going to order this weekend and rotate and do some more work to the truck next week. Thanks for all the advice.