What Viscosity Gear Oil Do I Use?

I own a 1988 Camaro with a 5.0 V8, I want to perform a tranny flush and I was told that I should do the rear end while I am flushing the tranny. What viscosity should I use, and is it for the differential or the Tranny?What Viscosity Gear Oil Do I Use?
read your manual luke


the lubes are totally differentWhat Viscosity Gear Oil Do I Use?
sae 90
the rear diff fluid for that year and make would be a 80w90 GL5 gear oil. If you buy Pennzoil it will already have the limited slip additive in it. If you buy another brand you may have to buy the limited slip additive and add it seperatly. And yes the fluid is different from the tranny. If it is a stick shift then it most likely takes either dexron III or GM Synchromesh which is a synthetic oil. You will probably have to get the synchromesh at teh dealership. If it is an automatic then it takes dexron III for sure. They dont make Dexron III anymore but they have superceded it with Dexron VI. Or you can get a multi-vehicle tranny fluid. The Dexron VI is very expensive. So look for multi-vehicle or most stores have a few more months to sell Dexron III before if just has to be called ATF.
manual trans use several diff fluids check owners manual or have parts store look it up by application. rear end 75w90 should work if limited slip use a friction modifier additive
they use different weight oil.the diff is a heavier oil and the trans is less.call a dealership,and get the correct weight. and this is a very good idea, and i need to do this on my pickup.... it's a messy thing,but it's worth it...and i would use a synthetic oil in both of them...
80w90. this i the most common gear lube. the tranny, if is it an auto. takes dexron 3 tranny fluid, and if it is a manual it takes 80w90 also. you can buy the expensive gm gl5 syncromesh oil for both but it is a little on the pricey side. i personally just use 80w90 for all rear ends and most manuals, although some maunuals use auto. trans fluid. the parts store can tell you the recomended fluid for your particular needs.