I did all three (front, rear and transfer) today on my SR5. Knowing that it needs 1.1 qts or whatever doesn't help since not everything drains out and oil is left in the tubes and pump. I tried my old method of using the pinky finger but for some reason I cannot feel the level. All three would start a slow drip which would not really change even if I added a few more pumps. I finally gave up and added a few pumps and put a bucket under the hole to let it drip for ten minutes or so. I guess another question is how sensitive are these things to a slight over or under fill?

 

open up the rear fill plug on the back of the housing, stick your pinky bend down and if it doesnt touch oil, you dont have enough.

 

Fill it up till it comes out the fill plug hole."big ok"

I'm serious.

 

what i like to do is drive around for about 15 mins, then let it sit for 5 mins then drain the rear diff, leave it for a long time, put the drain plug back in. fill it up till it starts to seep out of the fill hole, put the fill bolt back in and drive around for 15 mins, let set 5, then see where the fluid is at, if it needs a bit more, then put a bit more in.

reason for this is i have found that 80w90 doesnt really fill up the axle tubes like it should when just pumping it in, you have to let it circulate and drain to each side of the axle, then go back and top it off. this may put too much oil in the rear diff, but ive never had a problem with doing it this way.

if you are lazy, just pour it in till it seeps out the hole.

 

As for the sensativity question it may just slow you down a hair and i mean a hair. It doesnt really hurt to much but its not really the best to over fill. just dont under fill.

I like to fill till it pours out the fill plug and once its done coming out like that i close it up. If you tilt your diff like after a SAS sometimes then fill till it pours out then close it off and fill a bit more (i know a "bit" can be interpeted as a pour description but thats what i do)