Rear Differential Fluid Level 8.2
 

Greetings, all. I have a question that I think I know the answer to, but I just want to see what everyone else does. When filling the rear end of a GM product (like a 1965 GTO, for instance), I realize you use the side fill plug and fill until the gear oil drips out. That part is simple.

My question is: Do most of you check the oil level with the suspension hanging? I am sure millions of vehicles have been done this way and have been just fine.

But, in my usual "overthinking" mode, I am wondering if the rear end should be "raised up" to simulate normal ride height?

If you fill the rear end on a two-post hoist with the suspension hanging, that is one thing. If you fill the rear end on a four-post hoist, the car is at ride height as if it was driving down the road.

None of the above probably really matters, but I am curious to hear your opinions. Thanks!

Ok, my 2-cents. Given the location of the side fill plug and that the angle change from normal to full "droop" is measured in degrees, I don't think it matters at all. Was that your ultimate conclusion as well?

Hi Larry. To be honest, I haven't really come to any conclusion. I imagine it all doesn't really matter a bit, but I was just putting it out there to see if someone had a strong theory filling at ride height versus filling with the suspension hanging.

As I mentioned before, I am positive that millions of these differentials have been filled on a two-post hoist with the rear end hanging with no ill effects. Hopefully we get some opinions, however.

You’re overthinking it. :)

Just fill it with the car in a position where you can access the fill plug as easily as possible.

I would be more concerned about maybe 50 other things about my car then 3 Oz more or less of gear lube in my rear.

any 8.2 that ultimately suffers from a lubrication failure simply wasn't driven hard enough and should have failed far sooner.

Thanks!
 

Thanks gents! I kind of suspected that I was overthinking things. I just filled mine with the suspension hanging, exactly like ten million other cars have been done before mine!

As far as breaking the 8.2, I am not concerned. This rear has been completely rebuilt and this car is more of a family cruiser. I don’t run it hard at all. Any occasional full throttle acceleration is done when the car is at road speed and that doesn’t last long because speeding tickets suck.

Thanks!