Finished my 500 mile break in of the differential and will be changing out fluids tomarrow afternoon. I am inclined to use synthetic in front and rear (4x4) even though it's not necessary.

Also considering changing out my tranny fluids for synthetics. I only have 5000 miles on this truck and i'd like it to last at least 6 years!!!

Any thoughts on these?

 

I dont think synthetics in the diffs are a bad idea, but Ive heard that the synthetic in the tranny is no good in these trucks. Suposedly its slicker than the conventional stuff, and causes a little more slipping in the clutches.

 

Reallly ? Anyone else?

 

I just switched all my fluids to AmsOil, and am happy so far.

 

As for your Detroit TrueTac - you should use whatever Detriot recommends for it.

All my fluids are synthetic.

 

dunno about Detroit but my Eaton unit came with a care card specifying factory fluids and not to use synthetic.

 

The TrueTrac is mechanical and has no clutches so synthetic is fine. Synthetic is not reccomended for clutch type posi"s.

 

Synthetic everywhere but in the trans here. My trans builder (20+yrs) strongly recommends against synthetic. Hd 2 friends that switched to synthetic and got slipping within 500 miles and it went away when they switched back to dino. Having said that, there are plenty of people running synthetic with no problems.