Changing differential lubricant

[masospaghetti]

I was looking for a way to drain and refill my differential with synthetic lubricant but I couldn't ifnd the drain and fill plugs. What is the best way to go about doing this?

Thanks all.
-J

 

[Howard]

There is no drain plug you just remove the rear cover. The fill plug is on the front side just above a large web.

 

[scaperrotta06]

yeah just like he said but youll need to make a new gasket with black/ or blue rtv and let it dry at leat 2 hours
im doing mine today ill let you know how it went.

 

[Homerexplorer]

Like they said. Before you remove the cover, take a wire brush around the outside lip to loosen up the dirt and rust. Then blow it clean. When you remove the cover, remove all of the bolts but the top two. Carefully pry the bottom away. This will let it drain out without dumping - Get a large drain pan if you don't have one. Once you hav everything apart, tuck a rag in the pumpkin over the gears to prevent dirt from falling. Wipe the gasket surface with brake cleaner. Remove the rag. Clean the cover and then apply rtv around the edge. Carefully place it back on the pumpkin and bolt it up, tightening in a cross sequence (like a tire). Remove the drain plug with a 3/8" ratchet. Clean it with a blow gun to remove the metal filings (it's got a magnet crimped into it). Fill the differential until it drips out the hole. Apply a little rtv to the threads and replace the plug. Good luck

 

[budwich]

make sure you can remove the plug before you try removing your cover as people have had significant problems with getting the plug out depending on age / rust. If you drain everything and can't get the plug out, then you may have a problem as refilling will be difficult.

 

[dynamite196]

What's the process on the front diff since there is no drain plug and you can't really loosen the cover?

 

[ExplorerDMB]

You will need an evacuator. Basically just a pump with a hose on it that allows you to suck the fluid out and then allows you to put the fluid back in. That's really the only way without taking the front differential out completely

-Drew

 

[offset_98]

Just take it to Jiffy lube...$36 and its done.

 

[scaperrotta06]

in process

my rear diff is sitting rite now waiting for the rtv to fully dry but i have a question i bought 2 bottles of mobil1 75w 140 and 1 bottle mobil1 75w 90 and the friction modifer is it ok to mix the two different oils? i assume yes thanks
Dan

 

[aldive]

Just curious, but why would you want to mix them?

 

[ma96782]

Here is something from an old thread:

I ended up going with the Mobil 1 75W-90. Removing the spare tire made this job a LOT easier for me, particularly when accessing the fill plug. After loosening the bolts, I broke the old gasket seal using a putty knife and let it drain. I completely removed the cover and spooned the remaining oil out of the differential housing where it collects right behind the lip (maybe a cup or so?). Cleaning the old RTV from the machined surface of the differential housing was easy with the putty knife.

The absolute hardest part was cleaning the old RTV from the cover itself. I spent over an hour with the putty knife trying to get it all out. I didn't want to shortcut this part, though, for fear of creating a poor seal with the new gasket material.

I cleaned the magnetic fill plug, and also the magnetic bars embedded near the bottom of my plastic cover. Then, I cleaned the mating surfaces to make sure there was no extraneous oil remaining.

I used Permatex Ultra Copper Gasket Maker for the new gasket. Made a bead around the groove in the cover, stuck it on, torqued the bolts down, and let it sit empty for a couple of hours to cure before refilling with the Mobil 1. I bought a short piece of 1/4" fuel line (~18in. long) which I used to refill the differential. 5/16" probably would have worked, too, and helped the oil flow easier/faster, but I didn't want to risk it not fitting inside the fill hole and I didn't have exact measurements when I bought it. Anyway, there's plenty of space above where the spare tire normally sits to elevate a 1qt. bottle of oil, hook it to this short piece of fuel line, and let it flow through the hose to the fill hole. For me, it took just about 5.5 pints to get it within ~1/2" of the bottom of the fill hole.

I think Ford started using a metal cover the next year. I think I know why--my cover was cracked right through one of the bolt holes on the lower side of the cover. Looks like someone overtorqued a bolt in this cover's past (not me, this is my first time). I tried to find a new cover locally to no avail. It could only be ordered, and I needed my '92 back on the road! Fortunately, I spotted the crack before RTV'ing the cover back on the differential. I used some of the RTV to coat the inside and outside of the cover in the vicinity of the crack. I would've preferred a new cover, but oh well...

So far, no leaks after a couple hundred miles of driving (knock on wood). I don't think I'll bother with a new cover at this point, unless a leak appears in that area.

Aloha, Mark

 

[scaperrotta06]

...

i want to mix them because they only had 2 bottles of the 75w 140 and i had originaly bought 3 bottles of 75w 90 and swapped 2 for the 75w 140 and paid the difference i dont feel like going back out but if i have to i will so any 1 know if its ok to mix them?????

 

[ma96782]

Should be OK.

Like mixing engine oil.......no police is gonna come and arrest you. Though, I understand Aldive's comment.

Aloha, Mark

PS....book says........in case you wanna do what the BOOK says.

Traction Loc axle......Syn SAE 75W/140*
*Traction-Loc axles add 4 oz. of friction modifier when oil is changed

 

[aldive]

You will have no worries mixing.

Good luck .....

 

[ma96782]

Me......Since I'm only gonna do it, once in a GREAT while (change rear end oil)......I'd get the proper syn oil and modifier.........even, IF I had to make that trip to the store. I'm a worry wort........sometimes.

Aloha, Mark

 

[dynamite196]

Just take it to Jiffy lube...$36 and its done.

I'm guessing the evacuating pump is gonna cost at least that much?? Any chance of doing the back without using a pump to fill it?

 

[aldive]

I have used Mobil 1 and Amsoil synthetic oil in the rear and have never added a friction modifyer. Over 100k miles and all is well.

 

[aldive]

I'm guessing the evacuating pump is gonna cost at least that much?? Any chance of doing the back without using a pump to fill it?

Yes.

 

[daffy]

Diff lube

my rear diff is sitting rite now waiting for the rtv to fully dry but i have a question i bought 2 bottles of mobil1 75w 140 and 1 bottle mobil1 75w 90 and the friction modifer is it ok to mix the two different oils? i assume yes thanks
Dan

It kind of depends... do you have a limited slip? if so, you shouldn't use the 75w90, book calls for 75w140 w/ friction modifier. If you have an open diff, you're using a non-specified lubricant (the 75w140), and have no need for the friction modifier, a waste of money, IMO.

I fought this same battle in my head (I have a open diff) I went with 75w90 Mobil1. (after 2 trips to the store)

 

[aldive]

It kind of depends... do you have a limited slip? if so, you shouldn't use the 75w90, book calls for 75w140 w/ friction modifier.

I use full synthetic 75w90 in my 3.73 LS rear ens with no friction modifier.