I just read in my Chilton's that my 5-speed manual takes 3.4 quarts of ATF. Being an old school kind of guy this seems weird to me. We used to use it in the transmissions of some old 2-stroke dirt bikes, but cars usually got gear oil. Is this really the best thing for it, is synthetic ATF OK, and if there is a better alternative, what might that be?

 

I thought the same thing when I flushed my 3.4l m5, but ya use atf. As for synthetic I doubt it will hurt.

 

If you think from a gas mileage stand point, ATF is easier to turn than thicker gear lube.
Same reason for 10W30 to 5W20 engine oil weight, lees power given up in pumping oil.

 

if i understand it right, these transmission being constant mesh, need the atf so the blocker rings will work properly. Using tradition gear oil will make them malfuntion.

 

Not necessarliy, Muncie's, Saginaw's and BW T10's are constant mesh just like T5's and T56's. Same design, just different lube, easier to turn.

 

oh okay thats the only thing i could think of, for why it needs ATF