Solved 1999 explorer 4.0 SOHC 3.55 fluid change Axel code 45

[Lee's Automotive]

Hello is the differential fluid for the 3.55 rear differential 80W90 or 75W140 it's an open diff I keep seeing post about a tsb for all differentials that are 8.8 to use 75w140

 

[Mbrooks420]

75w140.

 

[Lee's Automotive]

75w140.

Ok would it hurt to use 75w90 instead?

 

[C420sailor]

So…the original spec was 80/90. Ford updated to 75/140 or whatever.

From what I’ve read, it wasn’t due to an actual engineering issue. It was apparently done to put most (if not all) their rears on the same fluid. Doesn’t hurt that their 75/140 is synthetic, and costs a pretty penny. That margin must be nice.

I stuck with the original 80/90. 327,000 on the original rear. Still looks great.

If you want to align with the TSB, or if you drive hard and/or tow, the 75/140 works. Nothing wrong with the 80/90 though.

 

[Lee's Automotive]

So…the original spec was 80/90. Ford updated to 75/140 or whatever.

From what I’ve read, it wasn’t due to an actual engineering issue. It was apparently done to put most (if not all) their rears on the same fluid. Doesn’t hurt that their 75/140 is synthetic, and costs a pretty penny. That margin must be nice.

I stuck with the original 80/90. 327,000 on the original rear. Still looks great.

If you want to align with the TSB, or if you drive hard and/or tow, the 75/140 works. Nothing wrong with the 80/90 though.

Oh, ok that's a perfect explanation would it affect my fuel economy, and should I use Ultra Black or buy the gasket?

 

[C420sailor]

In theory, lubricants can affect fuel economy. In practice? No significant difference.

The synthetic lube is the better lubricant, but is it worth the extra cost? That’s for you to decide.

As for the gasket…that seems to be a personal preference type thing. I like just using ultra black, as it simply does not ever leak. But changing the fluid is much more of a PITA. I’d like to get an aftermarket cover with a drain plug.

I think @donalds runs a gasket?

 

[Lee's Automotive]

In theory, lubricants can affect fuel economy. In practice? No significant difference.

The synthetic lube is the better lubricant, but is it worth the extra cost? That’s for you to decide.

As for the gasket…that seems to be a personal preference type thing. I like just using ultra black, as it simply does not ever leak. But changing the fluid is much more of a PITA. I’d like to get an aftermarket cover with a drain plug.

I think @donalds runs a gasket?

I found 75w140 from valvoline for 12.67 a quart at wally world

 

[donalds]

I think @donalds runs a gasket?

 

[Lee's Automotive]

View attachment 424205

What rear end do you have?

 

[donalds]

8.8 ls 3.73 gears

 

[Lee's Automotive]

View attachment 424205

How did you install the gasket did you use rtv at all and what torque spec? also did you use jack stands to lift it up?

 

[Fix4Dirt]

iirc when i changed my fluid+gasket i didnt use no rtv, it sealed just fine. used one of the top bolts to hold it, and then tightened em all down. unsure of the spec though. and i dont think these needs stands, theyre high enough imo, especally with my 31s

 

[Lee's Automotive]

iirc when i changed my fluid+gasket i didnt use no rtv, it sealed just fine. used one of the top bolts to hold it, and then tightened em all down. unsure of the spec though. and i dont think these needs stands, theyre high enough imo, especally with my 31s

Yeah, but I'm fat Haha and can't reach the fill plug

 

[Fix4Dirt]

Yeah, but I'm fat Haha and can't reach the fill plug

then maybe (?) jack it up till you can access. luckily it aint lowered, if it were a stang i would sure have to jack it up im spoiled with lift height,, makes so many things underneath easier, oilis a piece of cake, trans, etc etc

 

[Lee's Automotive]

then maybe (?) jack it up till you can access. luckily it aint lowered, if it were a stang i would sure have to jack it up im spoiled with lift height,, makes so many things underneath easier, oilis a piece of cake, trans, etc etc

Its time for me some 35s

 

[Fix4Dirt]

Its time for me some 35s

oh yeah what are ya waiting for!!!! get a RC lift, a BL, and some 35s!!!!!!! get crackin!!!! then youll have all the room you want, 5 with rc, 3 with bl, and 35s add 3 ((35-29)/2)and you can do a tt on top of that... thats lots of height!!!! the BL wont clear the diff or vroom vroom off anything else, but it will make more distance between the body and diff, so thus more headroom now what are ya waitin for?

 

[Lee's Automotive]

oh yeah what are ya waiting for!!!! get a RC lift, a BL, and some 35s!!!!!!! get crackin!!!! then youll have all the room you want, 5 with rc, 3 with bl, and 35s add 3 ((35-29)/2)and you can do a tt on top of that... thats lots of height!!!! the BL wont clear the diff or vroom vroom off anything else, but it will make more distance between the body and diff, so thus more headroom now what are ya waitin for?

Money HAHA

 

[Fix4Dirt]

Money HAHA

fair reasoning!

 

[donalds]

How did you install the gasket did you use rtv at all and what torque spec? also did you use jack stands to lift it up?

I just installed it dry as the instructions say
They give you a torque spec 18 footpounds
No jacking required I just remove the spare tire

 

[Lee's Automotive]

I ended up going with 3 quarts of Carquest 75W140 and this gasket everything is working perfect thanks everyone Amazon product ASIN B07Z8X85G1