I put Red Line Synthic ATF fluid in my tranny about 35,000 miles ago (time of the first oil change ever on the car)......

I have heard some people say that over time particals floating in the oil (from the gears/synrocs/etc...) can degrade the shift quality of the tranny....while others say manuals never need the oil changed....

so....what does everyone on here do?

 

Change the fluid! M6's don't have oil filters so I suggest changing the fluid on a regular basis depending on how hard you drive. Remember w/o the filter all the crap remains inside the tranny. The fluid is easy to change, only four quarts. Use something cheap like Costal ATF, this works as good or better than Red Line.
-Travis

 

I don't have the link here, But I found a site on the ZF gearboxes from the C4 Corvettes that did oil testing. They found that at about 16,000 miles the worn material from the transmission would start to build up in the synchros due to centrifugal forces seperating it from the oil. When I get home, I'll try to post it (you may want to PM me to remind me). But I'd start thinking about getting it changed....

 

Tell ya what either go by the manual or do like i do and change it once a year after i bring it out of storage

 

cool....I would like to see that site....


what kind of fluid does everyone use?

 

http://www.zfdoc.com/faq.htm


Scroll down 1/2 way...look for question:

(Q.) I just bought, at the local BMW dealership, 3 liters of the Castrol TWS 10W60 oil. I was surprised to see that it is motor oil. Not being a lubrication engineer myself, who did the investigation and determination that this product is compatible with and good for our ZF transmissions? Jim – Grand Sport Registry

 

That's a good link, trackbird. I've dealt with Bill Boudreau and he definitely knows his transmissions - especially the S6-40 and T56.

Also, just as an FYI and as Formula pointed out, Redline recommends that their fluids used in differentials, transmissions, or other gearboxes without filtration should be changed at normal intervals (i.e. no extended drain intervals as with synthetic engine oil).