differential fluid change coming up

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electrolover

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I have about 40k since the last time I changed the gear oil in the rear of my explorer. Had it done at the dealer with MC fluid.
The manual says 50k, but I will probably go ahead and change a little early and check for leaks while im done there. (Common problem with these cars)

Anyway, what would you guys recommend? Im thinking of running royal purple 75/140 but I may just go with M1 or valvoline synthetic in a 75/90. Any opinions?
 
do you tow? what weight is called for? Personally I'm a big fan of Amsoil gear oil but I'd use (in this order): Amsoil M1, Valvoline
 
Amsoil has an in between gear oil. 75w110 That's what I use. I even noticed at 15 degree drop in temp with it over the 75w90 amsoil that was in it before. It was hotter outside when I measured with the 75w110 oil. I guess there is a fine line between too thick and too thin.
 
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No, it has a hitch reciever but we dont tow. Just hual kids.

I think it calls for a 75/90 but not sure.
 
Just use what it calls for then. You already have 130,000 miles on it. It's not going to make much difference now. Remember most people don't even know you're supposed to change it. So if you've always been doing it every 40-50,000 miles it should last a LONG time.
 
Just checked our records. The dealer used 75/140 when they changed it. And charged $22 a qt! Lol
Anyway thats probably what I will put back in it. But I haven't made up my mind on brand yet.
 
the 140 is usually a sever duty. The 90 is fuel economy. In another8 words a Crown Vic in normal service its the 90. In cop car service7 its the7 140. BUT some diffs call for 140 all the t9ime. Check your specs.
 
Originally Posted By: electrolover
Just checked our records. The dealer used 75/140 when they changed it. And charged $22 a qt! Lol
Anyway thats probably what I will put back in it. But I haven't made up my mind on brand yet.



That is about right for the Motorcraft 75w140, they are proud of that fluid.
 
So I have checked around

My choices are
mobil 1 (special order) for $20
Synpower $13
Royal purple $22

And I guess MC is an option at $22..

which would you pick?

Im currently running the royal purple in my F150 and it seems to be doing fine.About 25k and it hasn't blown up, but I dont know that its any better than the others


Edit. I guess id be down with amsoil if the price is right and its a good fluid. Is any better for this app? What would it cost?
 
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Originally Posted By: hounddog
the 140 is usually a sever duty. The 90 is fuel economy. In another8 words a Crown Vic in normal service its the 90. In cop car service7 its the7 140. BUT some diffs call for 140 all the t9ime. Check your specs.


The manual calls for a 75/90. Seems there is a lot of talk about rearend failure on the web tho. Idk if its because people are getting leaks and running them dry or what. But it makes wonder if ford has changed their mind about what the best grade for the car would be.
 
Royal Purple MaxGear 75W90 and 75W140 are both excellent gear oils. I have run them both.
 
This is what I've had in my gearbox for over 50K and it's getting better with age. Not sure if it can be used in the diffs but worth a look.

Motorcraft XT-M5-QS
 
I used syntec full synthetic 75W90 in my silverado. Just did it at 80K mi. Fluid in there wasnt burnt and looked pretty clean. probably from all the top offs ive done over the years.
 
I've used RP, M1 and Amsoil. All are fine, use what's easiest t get and the best price.
 
Originally Posted By: bdcardinal
Originally Posted By: electrolover
Just checked our records. The dealer used 75/140 when they changed it. And charged $22 a qt! Lol
Anyway thats probably what I will put back in it. But I haven't made up my mind on brand yet.



That is about right for the Motorcraft 75w140, they are proud of that fluid.


Is it a Castrol fluid? Similar to XJ that they blend for BMW?
 
Originally Posted By: JHZR2
I've used RP, M1 and Amsoil. All are fine, use what's easiest t get and the best price.


Of the three it seems amsoil is the cheapest(not counting shipping)
 
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