I noticed that some of you guys have been running Mobil 1 synthetic tranny fluid in your 5 speeds. I just picked some up and was about to use it, but double checked my car manual.
The manual specifies GL-4, 80W90. Mobil Synth (and Castrol Syntec) gear lubes are both GL-5, 75W90. I figured that since the weighting is 75W90 whereas the car requires 80W90, the GL-5 would out-perform the standard gear fluid, right??

Wrong. GL-5 can corrode certain parts of the tranny, like synchros. Here's a VW article as an example;

http://www.concentric.net/~Sxs/Oils.htm

I'm retrning the stuff and going back to Red-line MT-90. It was great before. The only reason I was trying the Mobil stuff was because it was right there on the shelf at my store. Redline matches all our specs and exceeds, 75W90 and GL-4

Word to the wise

DW

 

GL-4 = Redline mt-90 and MT

 

How often are you changing yours? Were you changing it just cause it was old or do you do it routinely?

SuDZ

 

Dan B Martin, when he was around, corrected me on this. I quoted from the FSM that you never have to change your tranny fluid, which is true, sort of. But, if you tow a trailer or other such activity that loads up your tranny, then change it, I forgot the interval. I assumed that no-one uses their Max to tow. I think on this forum, that would be like 90% of us. Anyways, that's the deal.

I changed mine at 100K miles even though I didn't have to. I just wanted my tranny to last. Damn bearings had to go one me, and I still had a good clutch

DW

 

While most of us don't have to change the tranny fluid I still like the benefits of switching to a synthetic.

 

I have been gone for sometime but now am back. What happened to Daniel B Martin?

 

Search for a thread he started. He said he had to go away for a while. Hasn't been back since.

DW