The Stovebolt Site Forums The Shop Area Driveline How often do you change your gear oil?

I think the guys pretty much touched all the bases Kurt. But what the heck, I'll throw in my two
pennies worth just in case something was missed.

Change it if the truck is new to you as mentioned, just to see of there are any teeth in the
bottom.
Change it if you think it may have been in a flood or water over the running boards, they
can pick up water thru the vent or bearings.
Change it if you think it might not have the appropriate weight gear oil in them for the
weather ahead an plan on driving a lot, as Chris mentioned.

The main reason for changing the oil in the engine is contamination from the combustion
process. If the engine simply pumped air like a compressor then you would rarely need to
change oil, simply keep it topped off. The trans and rear axle are not exposed to
combustibles to contaminate them so they theoretically could go their entire life without
being changed.

However, even the theoretical non-firing engine will wear. Pistons, piston rings,
cylinder walls, bearings, cranks, cam & lifters all wear out. And with gear boxes and rear
axles the gears, bearings, bushings, syncros, shifting forks all wear out eventually also. What
wears off has to go somewhere so that alone would give reason to changing the fluids.
And this is the prime reason that the factory recommends changing the gear oil at certain
specified intervals.

Denny Graham
Sandwich, IL