If I remember correctly the M135/M211 originally only used 30W oil in the transmissions but they
changed the manuals later on to instruct the use of 10W in cold climates. My understanding is 30W
oil caused premature transmission failures in cold weather and the thinner 10W oil corrected the
problem. ATF fluid was either not available or was not as common to get back when the trucks were
made and that was why it wasn't used. Later on when ATF came out the transmissions were only changed
over to it upon being rebuild. The clutch pack inside the tranny had to be changed in order to work
properly with the ATF stuff. You were not supposed to just change fluid because the tranny wouldn't
work right afterwards if you did.
Bryan
1952 XM211 with a CCKW 5 speed manual tranny
1953 XM220 with stock automatic
XM105 1 and 1/2 Ton Trailer From Checker Cab Company
MVPA #20324
jonathon wrote:
>
> >... All you have to do is read the manuals and understand that
> >the trannys don't use atf, they use engine oil.
>
> That's strange, a guy I know that has an M-211 said that the engine oil is
> why they seemed to experiance premature failures and that is why he uses ATF
> with very good long term results?????? Certainly seems to be no absolutes
> with this stuff.
>
> je
>
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