Oldguard 7

Is it best to use a suction gun to draw out and add differential fluid or do I have to remove the bolts on the carrier?

7T1vette

Suction out what you can. Then throw in a little light oil or kerosene to thin what's left and suction it out too. Add one bottle of differential lube, one tube of Posi-trac additive, and fill till it starts to run out the "fill" hole with some more diffy lube. Plug it back up, then drive [slow] "figure 8's" in the Wal-Mart parking lot for a few minutes.

dannyman

If the car runs, take it for a spin to warm up the fluid before draining. Thick s**t when cold!

mrmarchuk

i never have been able to get all of mine out, got most of it but thanks for the tip on the kerosene!

Letournour 1850

I used pump and some thinner the very little I could not get out sould not make a big differance

Glassbowtie77

I suctioned mine out and couldn't get it all out either. I added the GM posi additive and then top it off. Since I changed it I've developed a pinion seal leak though.

Rich's'78

Did you use GM diff fluid as well? I once had a slow pinion seal leak. Changed the fluid and it stopped! Cheap to try.
BTW, when you have the old fluid out, insert one of those flexible maget 'arms' and route about the bottom of the diff to make sure there aren't any steel fines in there.