Change oil soon (& then some)

[Shannen Durphey]

Greg Hermann wrote:
This is not theory.

Happens more often than you'd guess.  We're talking about
transmissions that rely on splash type oiling. The mainshaft
front support bearing inside the input shaft usually fails. 
The rollers often come out blue, and the front of the main
shaft usually gets damaged in the process.  It may be
possible that the thicker oil simply can't get into the
bearing to do its job.  I only point it out as an example of
"thicker is not better."

One might be tempted to think the bearings fail first, then
gear oil is added in an attempt to quiet the noise, but I've
definitely seen it happen the other way around.

Chev light duty transfer cases also have trouble.  Oiling in
those boxes is marginal at best.  Accidentally replacing the
ATF with gear oil will cause the shift fork to fail.  Well,
it will cause the shift fork to fail sooner than normal. ;
)  After the shift fork fails, the gear it operates usually
goes bad, but that's nothing to do with the lubrication.

In my experience 90 weight gear oil in a light duty trans
spec'ed for thinner 10-30, 5-30, or atf will cause
problems.  However it sometimes does not hurt to add lifter
prelube or other engine oil supplements with EP additives. 
The only catch here is that the trans may contain paper
lined synchro blocker rings which can be destroyed by the
wrong additives. 

Shannen


> >>
> >> This can also happen in aluminum manual transmission
> >> gearboxes when the required ATF has been unknowingly
> >> replaced with traditional gear oil.
> 
> Usually only in the ones with a teensy little oil pump with a "microscopic"
> drive!
> 
> NON-EP type gear oils will generally be OK in most trannies--the sulphur
> and chlorine based additives in the  EP (hypoid) type gear oils will
> corrode some parts in many manual trannies, though.
> 
> Never seen ZDP additive hurt anything. And--oh BOY --does it give
> protection under extreme pressure conditions!!
> 
> Greg
> >>
> >> Shannen
> 
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