Hello,

I currently have the rear axle shafts off the truck.

I took off, cleaned then put on the rear diff cover.

I live in an area that does nothing but form rust anywhere and everywhere in very little time.

I don't want rust forming in the rear diff gears - can I fill the rear diff up ? Or will it leak out of the rear shaft holes ? Can I fill it up halfway then >?

Might be a stupid question but i figured I'd ask it before trying it and having it spill everywhere. Thanks

 

If your leaving it empty of the axles and it's gonna sit, then I would vote yes I would fill to the top of the fill oil hole. It has to be level on stands or it will loose some from opt he lower end. When you put the shafts in it's going to displace some oil. The axle seals on each end do need to be in to hold the oil in. The axle bearings on each end are also lubricated by this oil, behind the seals.

 

If you try to fill it to the bottom of the fill hole you will have oil running out the tubes before it is ever full.
I would not be concerned with immediate rusting. If you think about it, the top half never sees the oil until the gears are turning. Sitting around they never get oil.
At 17 bucks a quart I'd wait until ALL work is complete before filling it. Or if you're really worried put in 1 or 2 qrts. and spin it over by hand to coat the insides. Then throw plastic bags over the axle tubes for now to keep out dirt until you're ready to reassemble.