The transfer case is the easiest to change, given the ease of access. Used valvoline synthetic 75w-90, with the flexible container, to more easily pour into the fill hole.
Diffs really don’t get hot. You’re not talking much difference on the oil level. I’m still not sold on multiple changes. My 3/4 ton work truck that I only use for towing has 227k miles and no diff issues. Changed twice at 100k mile intervals.
That truck has 226k miles and was used for a company towing goosenecks for delivery lol. Average temp is about 185-190 meanwhile the breakdown is over 300F. Diff fluid is like boat lower unit oil and I've seen many 200k+ trucks that never have it changed. That oil isn't running through an engine dealing with combustion and compression. Unless you drown it in water that synthetic isn't breaking down. GM doesn't even list a change interval on the axels and says 100k for heavy usage. So it gets it every 100k. Runs and drives like a champ. If you want to go argue with GM feel free. My Land Rover didn't do it that often either and 12k intervals is an absolute joke on these diffs.
If it makes you feel better I did mine at valvoline just to see what the fuss is about at 17k miles. They absolutely didn't need it. Total cost for all three was $240
The first diff service is at 12k but the second is not until 60k. Still sooner than the 100k you reference, but thankfully it isn't every 12k. I'm assuming that first 12k is to remove any swarf from the building process and maybe the fluid has some breakin additives or something.
I just scheduled the 12k at RDS. I'm going to take the bath so as to not have to deal with excuses for rejected warranty claims.
If one were to install a clutch differential I'd consider a cooling cover, but, otherwise, these diffs should never produce enough heat to damage anything. If they are, there's something wrong with them. I picked up the AO Iron covers. Since he was at it and charged 300/ea, he should have cast some fins into them, but it isn't a deal breaker.
What diff covers are those???
They are on the Agile off-road site. Expensive for what they are, as a banks set that has cooling fins and air direction for my f350 are about 2/3 as much, but, I want the diff bomb proofed as we’re never gonna see easily available parts for these units.
