ok developed a leak in the rear end on my EX. going to fix it. was looking at the local auto parts store and they have 85/140 wt oil. is that ok to use or do i have to stick to 75/140?

 

It needs to be fully synthetic, and they only make it in 75W-140 or 75W-90. I used Mobil1 so you don't need to add friction modifier.

 

It will be fine.....just make sure it is full synthetic

 

Mobil one comes with modifier and without, make sure you read the bottle. Personally I would use it without and add a little pure modifier until the clutch chatter goes away on the circle test which would give you the optimal clutch functionality and slipping action. Depending on the clutch condition you might net even need it, or not much. I believe any of the top brands will work, and I am assuming you have a LS rear end, otherwise you are just wasting your money on modifier.

 

yea when i was crawling under i saw it called for 75wt-140 synthetic only. so thats what im going to get.

 

I put regular 75-140 in mine when I replaced an axle seal a few months ago because the store I was in didn't have synthetic. I'm not sure why it calls for synthetic, but nothing catastrophic has happened to mine yet. Should I rush out and change it to full synthetic?

 

I wouldn't worry about it, diffs have been using regular for 50 years and there are just a few good points about the synth, like higher extreme temperature ranges, works well with LS diffs with modifier, etc. When I was drag racing modifier always came in a separate little bottle for the reg oil. The front diff doesn't even "specify" synth.

 

All of my older vehicles use dino oil, and the rear axle in the Ex, which is really similar to the axle used in older F250s, has not always called for synthetic. The dino oil I used had modifiers in it already. I fully expect my opposite side axle seal to fail sometime soon, unless the other side failed for odd reasons, so I'll fill it up with synthetic then. Thanks for the additional comforting opinion.

 

so this would be ok?
Valvoline/1 qt. 85W-140 Durablend gear oil (281) | Gear Oil | AutoZone.com


or

Valvoline/1 qt. 75W-140 SynPower full synthetic gear oil (VV982) | Gear Oil | AutoZone.com

 

Yes ! that will work also......as Brent said......just make sure it has the modifer....or is ok for LS..........90 wt would work as long as it is full and has it's "whale oil" additive...........used for years on end.........there are just better choices out there these days

 

im going to get the Valvoline full synthetic 75wt-140. the material data sheet says it meets or exceeds the ford factory recommendations and not needing the modifier. now if my sore shoulder would just heal i can crawl back under there and fix it lol

 

It's really not that critical back there. Just a couple gears that ran fine for 100 years in non-synth.

 

If you have LS and more than 100k it likely needs clutches rebuilt anyway......mine does and I don't even take mine on anything serious off road......anybody know if there are upgrades for the stock clutches ??

 

my EX has only 84k. plus i dont do a lot of offroading.

 

Do you have limited slip DAZ ?