I'd like some advice concerning changing the rear & front axle fluid. I have two questions:

1. In the instruction manual (pg 454) it states, "Vehicles operated in normal service do not have regularly scheduled oil changes." Yet, on page 514, under service schedule A it says to change the fluid every 15,000 miles. I think I'm somewhere between A & B because I only tow about once every month or so.

2. I couldn't find any info on fluid capacity for both differentials. Do both axles take the same amount? If so, how much and should I use synthetic or is semi-synthetic OK?

Thanks for you help, guys....

 

The front differential holds just under 3 quarts. The rear differential holds just under 4 quarts. I changed my fluids to Amsoil full synthetic 75w90 in both front and rear (since i rarely tow over 10000lbs.) at 20000 miles and will probably check it again in 50000 miles or so. Diff fluid will last a good while if you use a high quality synthetic. I wouldn't put anything semi-syn or conventional in my diffs. Only full on synthetic. If you tow heavy every now and again, use a 75w110 in the rear instead of 75w90. If you tow heavy often or tow all the time, use 75w140 in the rear. 75w90 is fine for the front under all conditions.

 

Thanks, Bronco Hound. I appreciate the info....

 

I was changing the engine oil today with 14,300 miles now. I didn't think I needed to change my gear oil, but thought I'd check it anyway. The front was clean, but the rear looked dark with metallic swirls. I was a bit surprised since I'd never towed anything. I went ahead and changed the rear and left the front. I put 3 quarts in the rear which filled it to within a half-inch of the hole (about to the fill line stamped into the cover).

 

a good average interval would be about every 30,000 miles

 

BroncoHound gave sound advice; I agree...

I like the Amsoil as well as Schaeffer's. But the brand matters less than the quality. Use a brand name full syn. and you'll be fine.