I recently changed my tranny fluid and put in Pennzoil synchromesh. It was great at first but now after about 600 miles I am grinding into 5th gear on the highway at any rpms over 4000. Did anyone else notice this particular oil losing its effect after using it for a while? The car never did this with the factory gear oil. I want to know if I should just switch it to Mitsu oil or do you think something else is up. Thanks

 

Running GM synchromesh here for the past 6 k miles with no change...

 

redline has been great for me

 

I've run the Pennzoil for quite some time... your problem lies else where provided it is filled correctly.

 

There is a TSB out for 5th gear grinding. Mine started grinding after changing the fluids at 5K. I had to replace the whole 5th gear hub/synchro assy.

 

I had the penzoil in for 2 days and took it out. It is too thin of an oil (after talking with Penzoil). I replaced it with the redline Mt-90, which is a GL-4 oil. It does not shift into second well when the car is cold (socal cold..) but after a few minutes it works fine. To me the Mt-90 felt as the the synchros meshed better. Redline said to mix 2 qts of MTL (70w-80) and 1 qt of Mt-90 (75w-90).

 

DOnt get me started....TSB, 5th gear syncro replaced. Bad service job, replaced 3-4 syncro and the 5th again. Now, 6k later, same deal. Im going to TT to have it rebuilt soon enough...

 

Yeah i think id rather have it grind occasionally then let the genius techs at Mitsu touch my tranny. After they botched a transfer case install and timing belt job on my girlfriends old DSM, no thanks. Timing belt was installed one tooth off and for some reason when they did the transfercase under recall, the car came back with loose torque convertor bolts, no idea why they would have pulled the tranny for that. Yes I had to redo them both myself when I got the car home, because it took them 3 weeks to do it to begin with. dealers suck

 

Did you mix it like redline said or did you use straight MT90? Why would they say to mix them anyway? I might try this tomorrow cause I dont think the Pennzoil stuff is doing too well in my tranny. At times it feels smoother but other times its very notchy. The original fluid didnt have such a big change in feel for no apparant reason like this stuff is giving me, it has nothing to do with how hot or cold it is either, weird.

 

I have the BG stuff, Im going to swap it in today and see how well it does.