Differential oil

[chuckwagon101]

I have a 1999 Ford Explorer Sport......6 cylinder.....SOHC .....4 wheel drive....

How do I tell what WEIGHT rear transmission oil to put in? The manual says some take 70-90 and others take 75-140.

Thanks, Chuck

 

[Ronin8002]

It probably depends on the type of differential. Do you have an open or limited slip?

 

[chuckwagon101]

I have no idea.

 

[Ronin8002]

Post up your axle code from the drivers front door sill. We can figure it out from that.

 

[chuckwagon101]

On the door frame is a sticker that has the word "axle" among others. Under the word "axle" is the number 42

 

[Ronin8002]

that would be a 4.10 ratio open (non-limited slip).

75W-140 should be fine

 

[chuckwagon101]

I don't understand "75W-140 should be fine"


Is this the recommended oil for this differential?

 

[Ronin8002]

well I do know Ford used to recommend 75W90 but put out a TSB stating to upgrade to 75W140. 75W140 will work fine for you unless you expect to operate the truck a lot in sub zero temps, then you might want the thinner oil.

Edit: corrected 75W90 from typo of 80w90

 

[Ronin8002]

also the fact that you have 4.10 gears means that they could run a bit hotter than a numerically lower gear ratio. That, and if you expect to be running in hot weather, also suggests you might want the extra protection that the 75w140 offers over 75W90

 

[chuckwagon101]

Ok, thanks a lot!

 

[Ronin8002]

no prob

 

[Ronin8002]

Also, recommend as per the manual a synthetic 75w140 lubricant be used. Mobil1 makes a 75w140 that should work well for you