I have a 97 F150,with 3:55 open rear end.The tag says use 75W140 Synthetic oil only.Anyone ever heard of this weight? Where can i get it? Or can i put a different weight?Does it have to be synthetic? Thanx,Wayne

 

80W90 or anything near what it says on your tag will work just fine as long as you are sure it is not limited slip.

 

I have a 3:55 limited slip in my '94 Bronco. I have been using the 70-90 gear lube with no problems. Always add the additive however. Is there something I need to know about this weight lube and the limited slip diff?
Thanks


'94 EB,5.8,towing package, Rancho RSX7000 shocks,Westin nerf bar, Energy Suspension poly, keeping it basically stock

 

Are you changing the fluid, or just topping off? Synthetic fluid should not need to be changed unless you got water into it. If you need a complete change, you may have to go to Ford for the fluid. If topping off, the 75W90 Mobil One will work fine. Unless you have a leak, you should not need any.

Ford started using this fluid on the Lightning in the mid '90's and now uses it in all rear-drive axles.

Jim

 

Im going by what the tag says; looking at my cover there is a tag on the upper left saying "75W140 SYNTHETIC OIL ONLY";the tag on the upper right of the cover gives my gear ratio 3:55....i was just going to change it for periodic maint.purposes.I dont know what came in it,and there is no water in it.

 

Gear Oil needs to be changed regardless of which type you run. I myself have read the factory service manual stating synthetic oil does not need to be changed, but it does. Synthetic oil does not prevent wear, the diff still wears and needs to be serviced, which means clean it out. People that tow heavy need to do this more often. And people who take their vehicles swimming need to do this right away. You can run synthetic oil if you want, but it is not needed if you service your diff every 25,000 or sooner depending on your driving situation.

 

Its a 97 F150 XL,LWB,4.2 V6,auto,75,600 miles and as far as i know the rear gear oil is original.I bought it with 67,000 miles.And i only haul my self around.

 

If you live in a cold climate 80-90wt is fine, if your climate is hotter 85-140 is fine. In Arizona we use 85-140wt and the Northen part of the state is capable of 15 below, and no one has ever had a problem running 85-140 that I am aware off.

 

 

I just changed the rear differential fluid out this weekend and purchased this grade oil from Walmart, around $10 a quart, the Explorer rear took 1.6 quarts to fill completely.

 

holy 8-year-old thread batman!

 

very old! AutoZone doesnt carry any 75w140

 

Just this past weekend I bought some from Auto zone.
Mobil 1

 

I changed the fluid on my 2004 Ford F250 and used Valvoline 75-140 synthetic,,15.00 a quart at the parts store,,I did clean out the magnetic fill plug,,has some superfine sludge attached. The old fluid still looked really clean.

 

ok I have a 2005 F350 Harley Davidson. my rear diff cover is leaking. SO Im going to change it my self and use 75W90 or 80W90.

what would u use,