I just changed the front and read differential fluids on my 2005 CTT (160k miles). I changed the fluids when cold. Based or recommendations on this site, I used mobile 1 75w90 gear oil. Two issues that I'm concerned/wondering about:

1. On the front differential, I opened the fill plug first, and maybe 6-8 oz of fluid came out. This concerned me because I can only fill it until it starts to spill out.

2. Front and rear capacities are 1.1 qt and 1.5 qt = 2.6 qt total for both. I ended up being able to put in only 1.75 qts. total between front and back - I have 1.25 qts. left of the 3 qts I purchased. I'm concerned that both diffs are now low on oil.

I didn't jack the car up - I just put it in the highest suspension mode, so I assume that the car was level.
Should I have done this with the diffs up to temperature? Similar to how I had to do with the auto transmission fluid? I've not seen any instructions to that effect on my searching through the forums and on the web.

Any suggestions?

 

No, diffs need to be level only. The front diff is what initially launches the car... so, it gets the Lion's share of trashing. I had good luck filling a 50/50 mix of 75w-90 and 85w-130 gear oil in the front diff.