ZF 6spd oil change?

[sjd_sd]

My local (non-affiliated) shop suggested that I change my gear oil even though GM says its good for 200K. (my truck has 90K). They put 90W back in and now shifting from 2 to 3 is tough when cold and it makes a brutal grinding noise if its lugged with the clutch partially depressed. The shop is willing to change to the correct oil, so I'm hoping this gets cured. Has anyone experienced gear oil changes in the ZF? How frequently should it be done?

Thanks

[mgoodrich]

I changed mine at ~ 12K, along with all of the other fluids after seeing how the back end looked (lots of small metal filings in both front and back diffs).

I switched over to a synthetic equivalent to the ATF that was recommended from Amsoil. Same weight as the ATF I believe.

Surprised that they put in 90W. Once that is out, I think it (shifting) should return to normal.

[sjd_sd]

The mechanic was unable to find the recommended lubricant unless he orders a case, which will take 10 days. No local shops or even ZF distributers carry it. He's recommending using "Redline" synthetic transmission fluid, which he puts in Porsche's and the likes. Any thoughts on this?

[DmaxMaverick]

GM recommends Transynd synthetic ATF. Any good synthetic Dexron-III+ ATF should do well, including Redline, Mobil 1, Amsoil, etc.

Hard shifting? 90 wt. gear oil in place of ~10 wt. ATF....That'll do it! Tollerances designed for a light oil won't like that.

Keep your documentation for the mix-up. If your tranny fails prematurely, you may need it.

[sjd_sd]

putting in the Redline MTF has fixed the shifting problem. Unfortunately, the nasty grinding noise with the clutch partially depressed is still there. The mechanic thinks its the throw out bearing and that I need a new clutch. Any thoughts on this would be appreciated. I'm going to pose the question on the driveline forum as well.

[DmaxMaverick]

How many miles?

If less than 100K, it should still be under warranty. The clutch, and associated components, are covered by the 5 year/100K mile engine warranty. There have been a couple issues with the clutch, and TSB's to address them.

I'm moving this topic to the drivetrain forum.

[Racer67]

Does anyone have the number for this TSB?
I think I have the Flywheel issue and every time I go to my local dealer and ask about a TSB they say they can not find anything on the problem
I have.

[dmaxmule]

sjd_sd,
I have the same grinding noise as you when shifting from 2 to 3. My dealers mech. did not ever hear the grinding and said it was normal. How did you ever show your dealer the grinding noise?????????

Thanks dmaxmule

[sjd_sd]

dmaxmule - sorry about the slow reply, I thought I had responded.

My truck was fixed under warranty...bad dual mass flywheel. Dealer in Fremont was pretty cool about the whole thing. It runs fine now. They didn't even mention if the clutch was worn. Maybe they were afraid to tell me 'cuz I was so grouchy about bringing the truck to the shop AGAIN.

I'm at 92K and hoping to get a few more years until either Chevy makes a reliable truck or Toyota makes one that I can put some stuff in the back of without making it drag its bumper down the road.

Good luck.

[BozDMAX]

Might be Bulletin No.: 04-07-31-006A

Date: December 09, 2004

TECHNICAL

Subject:
Excessive Shifter and/or Engine Vibration, Bearing Growl and/or Rattle Type Noise While Depressing or Releasing Clutch Pedal (Replace Flywheel and Flywheel Mounting Bolts)

Models:
2001-2005 Chevrolet Silverado
2001-2005 GMC Sierra

www.alldatadiy.com has the complete list of TSBs (and a whole bunch else).