Gear oil for Explorer 8.8 with limited slip?

[ColoGuy]

Manufacturer recommendations are designed for the typical user in a typical environment. A "one size fits all" recommendation. If one operates in Fairbanks, Alaska where the temperature may be -70F and frequently pulls a camper their needs are different than a typical driver in Houston, Texas.

Spent an evening perusing youtube for gear oil knowledge. Frankly I don't think many people know jack about gear oil. I found exactly one video that was helpful, it only had 7000 views in a year. People loved the video where the diff cover was clear and they could see the gear oil being thrown around. That had a million views.

Sorry I bothered this board with a gear oil question though. Geez. From now on I'll probably just consult with my owners manual - when it shows up. Or maybe try the Jeep forum where people actually try to help instead of insult.

 

[donalds]

You asked we have the spec

The jeep remarks was ha hit below the belt
Don't let us give you the wrong impression we aren't all that bad

Any oil you will like will work just don't forget the friction modifier it's important

 

[gmanpaint]

For normal use, use whatever floats your boat, but as what was pointed out, the factory specs for what's called for is the best choice as a standard. Just adjust to your personal use.

I off road a lot, in low range with deeper gearing than stock offers, and hard on the rig. I encounter deep water crossings frequently. Because of that, I change the fluids out after a couple outings, regardless of miles, or calendar time. The differential gets hot, and when it hits cool water, it creates a vacuum, and sucks water in past the axle and/or the pinion seals. Water & oil, well you know what happens. Condensation can also happen and introduce water to the fluids. That can take years and years to happen tho. For that reason alone, I would change the fluids out at least every five years or so.

If nothing else, use synthetic, because used conventional gear oil STINKS bad!! It gags me, and I can't deal with it! LOL!

To the new OP... Don't be put off here. You need to realize this forum has been around for decades now, and has hundreds of thousands of registered members world wide, with millions of posts. These 2nd gens have been discussed here over & over constantly over that time, and the information you seek, has been posted multiple times already. If your search results do not come up with what your looking for, try different key words in different orders. I searched for 8.8 gear oil, and hundreds of results popped up instantly. The members that frequent here daily, are normally very well versed in these vehicles, and know what they are talking about. Either with personal experiences, or from reading others comments, and retaining that knowledge to help others when the time arises. Granted, sometimes the etiquette slacks off, but sometimes one might be having a bad day & not feeling like being nice for some reason. That's no excuse, but it happens. Most will realize it later, and normally apologize. If they don't, just remember this is the internet, and you have to have thick skin at times. Mods are here to make sure nobody breaks the rules, and step in when it does happen. Bad mouthing or bullying is not accepted here in any shape or form.... From anybody.

With that said, I hope you stick around, learn your way around the forum better, and interact with others peacefully along the way. The forum works when share what you know, and learn from other's at the same time, while keeping an open mind. Yes, this goes for everybody, not just you.

 

[masospaghetti]

My guess is that Ford went to 75w-140 so they could advertise it as a "lifetime fill", because it will provide adequate lubrication for a longer period of time compared to 80w-90.

Also, Ford spec'ed this oil to hold up to the harshest conditions (max payload towing for example), so for a daily driver is probably doesn't matter.

That said, the price difference between 75w-140 synthetic and 80w-90 conventional is not very much. It's maybe an extra $15 for the fill and lasts 100k miles? Why not just use the correct fluid and call it a day?

 

[BKennedy]

I have used Vavoline synthetic 80-90 for years in my Ranger and Silverado. Started using Lucas 75-140 in the Explorer because its recommended for my Eaton E-locker, and the Detroit locker. It is like sticky syrup, but really works well. I like the heavier grade because I really don't care about mileage in my off-road vehicle. I have found the best prices for Lucas through Summit Racing. I have never needed friction modifier additive for synthetic gear oil.

I have never seen a thread this long about gear oil. Buy what you like, it really doesn't matter all that much for a daily driver.

 

[56_F100]

I'll add another bit of info. Bought a 1997 Explorer with 4.0 V6 new. Sold it with over 160k on the clock. I know the new owner and she has nearly 200k on it now. It came with the 8.8 and locking 3.73 gears. I live in eastern Washington state with family in Montana & Wyoming. Granted it's not Alaska, but temps where the vehicle was used vary from well below zero to over 100 in the summer. Did a lot of towing, didn't baby the rig but did keep it well maintained. My gear oil of choice was Amsoil synthetic 75W-140. My choice was to change the lube on a regular basis.. Amsoil's tech sheet said friction modifier was not required (they do offer it) so I didn't add any and never had noise or chatter from the diff. Just the facts.

 

[Justinwht]

Differential oil question

 

[Balke]

Hi ::,,If you read my post in the "" New Members Intro " section of this forum , now on page 17 , posted Aug. 12 / 2019, titled " Hi I am Blake "" then you will know my story . I just recently did my own gear oil change . My manual says that it never has to be changed or even checked unless the diff. had been leaking , totally submerged in water , or if service has been done . I saw evidence of past leakage , and total submergence in water . ( fishing line and lots of sand in the rear upper frame body cavities )) so I bought a gasket and did the job . My manual said to use synth. 75 / 140 and add F. modifier. I found no gasket , and only about 1 qrt. of oil.
I used a brand that I found on store shelf , called " Royal Purple Synth. 75 / 140 c/w friction modifier ""
In Canada that stuff is like close to $30.oo a bottle . I am about 1 tenth of a qrt short my capacity is just over 3 qrts.
ya ..the oil is actually purple colored and very clear . Yep, my Diff is S613E 3L73 88 OBO5
I am thinkin that the " 88 " means 8.8 ' Yep !! I got me a 10 bolt 8.8 Possi . with brand new Royal Purple , and the only sound I hear is :: ooooooaaaaaaahhooooooaaaaahhoooooo.

 

[410Fortune]

"My guess is that Ford went to 75w-140 so they could advertise it as a "lifetime fill", because it will provide adequate lubrication for a longer period of time compared to 80w-90."

Actually Ford went to 75W-140 spec because the dealerships no longer carried anything else.

Yes I understand full synthetic gear lube runs cooler and gets better MPG it has been proven. This is why the dealers swapped to full synthetic, The OEM's are always chasing the better MPG goals to keep up with the stringent EPA demands for California / North America

The rear axle is still the same rear axle that had 80W in it previously


Did you guys know the NP205 t case was used from 1969-1993?
NP205 gear driven transfer case came from the factory with a few different fluids in it, in 1969 it had gear oil in it, towards the end of its run it was shipped with ATF in it
The inside of the t case never changed.
People still debate me when I tell them I filled ours with full synthetic ATF.....YOU CANT DO THAT! I hear....lol well its been running like that for us for over 4 years now......
Its the same gear driven t case it has always been
research is your friend

Discussion forums are the perfect place to get opinions and have constructive DEBATES about what fluids work and what doesnt.....do all your reading, take all of your notes and then YOU make an INFORMED decision on what works best for YOU.

 

[BruceExploder]

Prob should change mine huh? Lol

 

[fast_dave]

 

[Mountinheer]

I like Redline 75w-140NS because it is synthetic with no friction modifiers. Good for my truetrac, but also good for 'tuning' grip of a friction plate LSD by adding certain amount of the slippery stuff.

 

[sidneyhop]

Is it important to use the Motorcraft friction modifier or can I use this? K&W 402508 Trans-X Posi Trac Limited Slip Gear Oil Additive - 7 Fl Oz. I just happen to have it already in my garage.

 

[BKennedy]

Any friction modifier should work fine.

 

[sidneyhop]

Any friction modifier should work fine.

My confusion is, is a 'posi trac limited slip oil additive' the same as a 'friction modifier'? The one I have is 7oz, per use Im assuming, and the friction modifier is only 4 oz per use. Do they do the same function?
My symptoms are it seems to grab or bind slightly, most noticeably in the morning when I first start driving, but also during acceleration.
Thanks

 

[410Fortune]

Yes they are the same thing
Limited slip additive is friction modifier

Adding some will allow more slip and less grip it also prevents the gear lube from "foaming"

The factory limited slips can work really really well until they wear out, it is fun to watch them work from outside the truck

Grabbing when cold and under acceleration is what you want a limited slip to do, it will lock both tires together until it slips.....sound like your factory LS is still working

 

[sidneyhop]

Grabbing when cold and under acceleration is what you want a limited slip to do, it will lock both tires together until it slips.....sound like your factory LS is still working

Thanks for the info!

 

[C420sailor]

I’ve used Valvoline 80W90 simply because I never knew Ford updated the spec. That said, I baby my trucks, and I change the fluid somewhat regularly. It comes out looking not very different from when it went in *shrug*

My 98 just hit 300k. Original diffs and gears. I’ve had to replace all the seals in the front, but the rear has been an absolute champion.

As long as the 75W140 isn’t much more, I’ll probably switch to it.

 

[donalds]

I’ve used Valvoline 80W90 simply because I never knew Ford updated the spec. That said, I baby my trucks, and I change the fluid somewhat regularly. It comes out looking not very different from when it went in *shrug*

My 98 just hit 300k. Original diffs and gears. I’ve had to replace all the seals in the front, but the rear has been an absolute champion.

As long as the 75W140 isn’t much more, I’ll probably switch to it.

Believe me it's more