Synchromesh fluid = gear oil?

[neo3]

I'm thinking of trying Pennzoil Synchromesh in my t56, due to occasional "crunchy" shifting (1-2 shift, sometimes 2-3). Currently using Redline D4 atf for the last 8K miles or so - it is so far the best I've tried but hasn't totally fixed the problem. Anyway what gives me pause is the following warning in the t56 service manual (all caps in the original):
DO NOT USE GEAR OIL IN THE T56 TRANSMISSION SINCE THIS MAY DAMAGE THE BLOCKING RING MATERIAL.
My question is: is the Synchromesh considered a gear oil? Or do they probably mean the heavier diff-type gear oils? I've read a lot of posts about people using Synchomesh in the t56, saying how well it works, but nothing over a long time period.

 

[MolaKule]

Sounds like you need to try our SynchroGlide.

http://www.specialtyformulations.com

Gear oil usually refers to a 75W90 differential fluid. Different fluid, different application.

Gear oil would be WAY too thick (too high a viscosity) for the transmission.

Synchromesh with a capital "S" usually refers to a manual transmission fluid of approx. 9.0 cSt viscosity with special friction modifiers.

[ June 01, 2005, 06:36 PM: Message edited by: MolaKule ]

 

[mechtech]

neo - Nothing wrong with Penn Synch, but go right to the top and get a
S.F. in a suitable viscosity.
If it doesn't work, there is someting wrong with your trans. Period.

 

[Mike_dup1]

SAE 5-30

 

[Idrinkmotoroil]

some people claim Redline D4ATF has killed the synchros in that transmission as they are carbon based synchros. Redline told me they have never received any complaints but a few people have reported damage on the internet, might just be an urban myth, dunno. I couldnt' see Synchromesh causing any damage, but I am not sure exactly what kind of fluid would damage carbon fibre synchros.

 

[unDummy]

Doesn't it require an ATF like Dexron?
How about Redline DexII instead of the D4? or Mobil 1 ATF? or RoyalPurple MaxATF or Synchromax? or Torco's ATF and ATF?
Wouldn't MTFglide be a better choice then Synchroglide?

And, BG SynchroShift II is another option that is a rarely mentioned excellent fluid.

 

[neo3]

quote:

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Originally posted by Idrinkmotoroil:
some people claim Redline D4ATF has killed the synchros in that transmission as they are carbon based synchros. Redline told me they have never received any complaints but a few people have reported damage on the internet, might just be an urban myth, dunno. I couldnt' see Synchromesh causing any damage, but I am not sure exactly what kind of fluid would damage carbon fibre synchros.

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Yeah I've seen lots of postings about this, or t56 + synthetic. Actually for mine (2000 fbody) the claim is synthetic will ruin the paper block rings. Interesting that my owner's manual doesn't say anything about not using synthetic. Anyway I think some or all of those ruined synchros are due to abuse, like "powershifting". I recently saw a thread about this, apparently one form of powershifting is to keep the accel to the floor, don't bother using the clutch, and slam the stick as fast as possible! Not something I would ever try.