Changed fluids today

Roofer · December 19, 2002

I changed out the front and rear end fluid on the HD today. I went with 75W-90 Mobil1 synthetic. It was an easy job, thanks to help from SoMNDmax. The rear end fluid was as black as engine oil that had not been changed for 5,000 miles, and just a few shaving on the magnet. The front end had lots of shaving, but the fluid still looked good. Both were a tad low on fluid, but not bad. I'll be doing the F550 next, I'm sure it needs it. I recommend this to everyone who has an extra $50-$60 laying around.

BTW, I have almost 11K on this truck with only one long tow on it.

I also upgraded to 265 tires and put on a new tranny filter.

gomer · December 19, 2002

i also did mine this weekend but i only got to my rear end and diff case. my rearend was pretty clean and my diff case looked brand new. my truck has 50g miles on it so changing fluids is cheap insurance. my buddy took his 99 1/2 ton sierra to a mechanic to get his fuids changed(rearend,diff,front diff,and tranny)and paid 250 bucks,screw that! i got around 45 bucks in mine right now untill i can do the tranny and front diff

JimWilson · December 20, 2002

I think your oil weight was okay for the rear diff, but I believe you put the wrong weight oil in the front. Isn't it supposed to be 80-90?

Roofer · December 21, 2002

I think your oil weight was okay for the rear diff, but I believe you put the wrong weight oil in the front. Isn't it supposed to be 80-90?

I think you are right. That is the GM spec, but I just ordered all the same oil. I'm sure it won't affect anything. Definitely better than not changing at all.