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just the other day i happen to notice that there is a small wet spot on the back of the rear diff cover. so yesterday i pull her off and find that a small bit of rust had lifted the silicone on the top allowing a little oil to escape. no big deal. i cleaned up the rust and used "the right stuff" to seal it back on. so then i go to my garage to find some 80w90 to put in and i read the tag on the diff that says 70w140. ??? now i open the manual and read about synthetic oil, never needs replace.
now my question
i filled my open diff with 80w90 to the fill hole and installed the plug. is this a problem?
doesn't the rear axle have a vent? mine does. does this vent go to atmosphere?
hopefully some one that knows can help me. i have other questions but the depend on the answers.
you are supposed to fill it till it runs out the fill hole, yes it has a rear vent and it goes to the atmosphere, but the hose or the barb on the axle can get clogged fairly easily
so if the rear vent is open to atmosphere than it can suck in dirt. if it can suck in dirt than it needs to be changed. even if it is synthetic.
any ways is 80w90 doing any damage to these bearings.ie are they something special?
You shouldn't be getting any dirt in through the vent tube. Offroaders extend the vent tube and run it up even higher so water and mud don't get in there. But they know to change their fluids often enough anyway.
I'd follow the owner's manual recommdation for both gear oil type and interval.
i would run the heavier just because they say to....those diffs get really hot
yes they take in minute amounts of dust through the tube....thats how the tiny pin hole in the barb on the axle gets clogged, dust over time mixed with gear oil seals the hole up
towed our trailer yesterday jsut over 100km. trailer weighs about 5000lb. when i got where i was going the rear diff was quite warm, border line hot. i'm going to switch the oil back to the 75w140 syn.
thanks for the responces