Transfer Case and Differential Oil Change

2000 Blazer 4wd.

Owner's manual says to just top up the oil in the transfer case and differentials (front and rear) every 2 years, but mechanic suggests to drain and change oil completely.

What is necessary? Thanks.

Chiltons says rear end every 15k.
Not sure about the T-case.

I change my transfer case fluid every 50,000 miles. I figure better safe than sorry.

I drain and change all of them every 30K including greasing the drive shaft fittings. The fluid in the differentials and transfer case always looks really clean though.

I change my transfer case fluid every 50,000 miles. I figure better safe than sorry.


....Definetly!! better safe than sorry. I was about to go wheeling with a couple buddies back in '03 with 82k on the odo. and figured since i got her at 70k might as well change the transfer case and front and rear fluid beforehand since i had no maintenance history. Glad i did. The tranny fluid inside the transfer case was brownish, similiar to burnt fluid in the tranny. The differentials had fairly discolored tints, but didnt think too much of it, just glad i did it.

Any hints or tricks on making the fluid change on the front diff any easier? Doesn't sound like much fun.

Any hints or tricks on making the fluid change on the front diff any easier? Doesn't sound like much fun.


Depending on yourbvehicles age and rust buildup its a simple crack the drain plug and filler up, my '97 blazer was easy but My '91 bravada had a rusted and rounded out front differential oil plug and fill plug. That was APITA to get out the bolts and put new ones in. I would also advise a pump setup cause its tough to fill without one.

Haven't looked yet, but Haynes claims there isn't a drain plug on the front, only on the transfer case.

AdvanceAuto sells a pump that fits into a gallon gear oil bottle perfectly.