Rear end synthetic?

[allen820]

Is it a good thing to change rear end lube to synthetic? If I do that, should I change out the new fluid after a couple thousand miles, in order to eliminate any dino which remained after the change? Thank for the info.

 

[RiverRat]

You might get a few additional .xx mpg. If you are towing I would suggest using synthetic. I wouldn't bother changing the fluid a second time to get the dyno juice out.

FYI, I'm using semi synth Valvoline durablend 85-140.

 

[dogfriend]

All of the Syn Gear Lubes I have seen (Mobil, AMSOil, Redline) state that they are fully compatible with conventional (dino) gear lubes. No need to change again if there is a small amount left behind.

 

[SteveVB]

Synthetics were stock in the rear axles starting in 95 I think. So it likely was filled with syn gear oil 75w-140 from the factory. My 4.10 disc rear has a tag on it - may want to check.

Good Luck

 

[RFR2212]

I did the synthetic gig fer a bit and noticed nothing... went back to dino in the diffs... but then again, regardless of wind rain snow sleet or Godzilla, i get 10mpg! And life goes on!

 

[Robert]

Starting in '95, ford put synthetic fluid in the rear differentials for all 3.73 & 4.10 axles as well as all V8 equipped Explorers. If the Explorer came with a 3.27 or 3.55 the rear axle came with conventional dyno oil.