Changed to Mobil1 syn ATF, didn't help
 

So it was suggested by other members to change the trans fluid to Mobil1 syn ATF as a possible remedy to notchy shifting on the M6. So I tried it but after driving the car for a couple hundred miles I think it is worse now than before. Still got notchy shifting especially going into 3rd gear. I know this has worked for some but not for me. Just letting everyone know that changing to Mob1 may not help. I may go back to GM fluid.

Was it notchy before your Hurst install? I know there are a few who have put in the Hurst and have not liked the way it shifted.

My trans was notchy going into 3rd as well, almost since new. I tried two different fluids including Mobil1 and neither helped. I finally had the trans torn down to add some hp parts and my builder found it to be quite a bit out of spec. Needless to say it shifts like butter since being re-assembled within spec.

It was notchy even before the Hurst. The dealer said nothings wrong and let them know if it gets worse. 2nd time in they still said nothing wrong. Thats when I installed the Hurst hoping for improvement but same thing, only maybe a little worse with the shorter throws. I decided to try the Mobil1 but still same thing. Should I replace the fluid with stock GM and take it back in to the dealer? I know they'll say "it's the aftermarket shifter".

Bump. This is a topic I'd like to know the answer to as well.

Well, they should have on record that you have brought this in before for the same thing with the stock setup. Seems your syncros are out of wack. See if they will adjust them under warranty.

OK, GM won't agree, but drain the fluid and replace with a straight 30w motor oil with 5-6 oz's of Lucas oil treatment.

Try this and post back. I think you will be surprised.

:popcorn:

If someone has the "grapefruits" to try this, and report some good findings, you'll be my hero :bow:

I've been to the dealer twice with this, and have heard the same thing.... " That's normal for this transmission " :facepalm:

I strongly believe the issue is tolerance related and changing fluids is a band-aid fix. Unfortunately pulling and disassembling the tranny is a large job and GM isn't going to do it unless they see a catastrophic failure. Same as the clutch sticking issues.

Well I'll bring it in 1 more time and insist they take a closer look! I wonder if I should replace the fluid with stock GM before bringing it in.

Better safe then sorry.

and they won't acknowledge that either ... :cry:

My point exactly. When you take your car in to have the service dept look at a shifting issue or a sticking clutch pedal do you think they pull the tranny to inspect hard parts? Not a chance in hell. At best they change the fluid, bleed the clutch, take it for a test drive and tell you everything is fine.