75W-140 required in Explorer 8.8?

[Scott88]

Gentlemen, the owner manual for a '99 Explorer(4.0 SOHC) with a 3.73 LS rear axle calls for synthetic 75W-140 plus friction modifier. I'm not one to deviate too far from from the manual for my own amusement, but is that thick of an oil really needed?

The two vehicles in my sig(both use rear 8.8 axles and I'm runngin synthetic 75W-90) call for 80W-90. Which makes me wonder why the Explorer would benefit? It will not do any towing or otherwise be submited to anything too demanding. Your thoughts? Just curious.

Thanks!

 

[The motor guy]

if the two vehicles are cars then that's probably why. They care more about fuel mileage. An explorer will put more of a strain on the vehicle

 

[exranger06]

My Ranger has basically the same 8.8 rear axle (although it's the 28 spline version as opposed to the Explorer's 31 spline) and it calls for 80w-90 with friction modifier for the limited slip. I would think a Ranger would have just as tough, if not tougher duty cycle than an Explorer.

 

[Whimsey]

Do you tow or carry heavy loads? If not then using a quality synthetic 75W-90 with the appropriate LS additive will work fine. I had that in my F-150 with the 8.8, no LS, and it was fine. Unfortunately the indy shop used Blue Permatex and it developed a leak after about 2 years. Took it to Ford to fix and they used their 75W-140 and the Ford cover sealant. No leaks so I'm not spending any more money to replace rear diff fluid that has been changed 3 times in less than 30,000 miles previously, now have 50,000 miles on the truck. The truck sees about 5,000 miles per year, light duty service. It's good till the truck rusts out.

Whimsey

 

[97f150]

I just changed the diff fluids in both of my trucks. Both call for 75w-140, yeah almost a bill for just the oil. Even my 97 F-150 called for 75w-140, my Ram came from the factory with 75w-90 and that was later recalled to switch to the 140 for whatever reason. Dodge also wants it changed every 30k (yeah right), both 97 and 05 F150 said the fluid was good for life (another yeah right), I think 50k would be a happy medium to change. In an Explorer that won't tow anything I would think 80w-90 will be fine changed out every so often. I sometimes wonder if Fords filled for life [censored] is the reason they spec an oil like that.

 

[Scott88]

Thanks guys for the input.

No towing. Only hauling it would do on occasion would be 5 adults + luggage. It would be changed every few years.

I'm leaning toward Valvoline Durablend(gear oil of choice, if not using synthetic) 80W-90 + Motorcraft modifer unless I should play it safe and go thicker.

 

[Jeff_in_VABch]

Going thicker in a non-towing application will waste power and fuel economy.

I would go with the M1 75W90. It's thin for the spec and will give as good of performance as you will get.

 

[Dick in Falls Church]

You could also try a 75W-110

 

[Rand]

Originally Posted By: Jeff_in_VABch
Going thicker in a non-towing application will waste power and fuel economy.

I would go with the M1 75W90. It's thin for the spec and will give as good of performance as you will get.


the question wasnt going thicker...

ford spec is 75w140.

I would just use the 75w140. The explorer isnt exactly lightweight.. esp if you load it up or tow.

if you use a good syn gear oil you wont lose much gas mileage.

 

[DrDusty86]

Use the 75w140. Ford must think that the duty cycle/ explorer usage calls for it for a reason.

I had a ranger 3.0 w/ a 7.5" and used Mobil 1 75w90. I used it to tow 3500lbs on occasion. Never had a failure in the 413,000 miles I had the truck. I have no idea what the 7.5" calls for, I just used M1 fluids everywhere including power steering pump.
Dusty

 

[01rangerxl]

Ford started using and recommending 75W140 in the Explorer and Mustang, and possibly other vehicles, to cure noise from the differential. I'd use it.