I recently added a mag hytec cover to the sterling 10.5 rear. I used the recommended royal purple 75w-140. I am now replacing the front differential cover and I am not quite sure if using the same grade of gear oil is correct or 75w-90? Any advice?

 

If I recall correctly, the front axle is spec'd for 80w-90.

 

Ford says 80W/90 synthetic for the front. You will probably only find 75W/90 at most stores, which I think is fine. I would not use the 140. That is quite a bit heavier.

 

I have read the owner's manual and it said 75w or 80w-90 i can not remember.... however, the mag hytec instructions called for 140... same as rear diff. I will follow w/ 75w-90. Thanks for the replies.

 

There is really good stuff in the tech folder.

Welcome to guzzle's Front Differential Maintenance Web Page

 

Ya I read the tech folder thread. it called for 90 as well. Mag hytec through me off w/ their instructions for 140 on the front.

 

Why would Mag Tech specifiy what weight oil to use?

 

Exactly - Stick with the OEM reccomendations.

 

Hey guys, while we're on the subject, I'm doing both front & rear mag hytec swaps this weekend. Any idea how many quarts the front & rear hold? 03 250 SD.
**Nevermind** - should have checked Guzzles website first, already answered my own question.

 

Does Guzzle have the Mag-Hytec install? Because the capacities are not the same as with the OEM cover.

Anyway, the Mag-Hytec site has info:
http://www.mag-hytec.com/Ford%20Diff...2-10.25_.5.pdf

http://www.mag-hytec.com/Ford%20Diff...2050_60-FF.pdf

They have the wrong oil recommendation for the front, which has been noticed by others. So use the Ford lube spec, and the Mag-Hytec quantity.

 

Just curious why you would put a mag hytec on the front diff? I can't see any benefit from it unless you ride down the highway towing a load in 4wd.

 

I agree.
When I changed the oil in mine the rear definitely looked like it had been "used" but the front looked like I just drove it off the dealers lot.
This was after 70K on the clock and I use the 4WD weekly on jobsites.

 

I just replaced the front yesterday. Easy installation on both. 1st question answer is 5 quarts only in the rear diff and just under 4 quarts in the front. 2nd question answer is I chose mag hytec for the look and assurance. The astetics are awesome. I will try and post pics. But the biggest reason is maintenance. I like being able to check the fluids w/ the dip stick. Also, as long as the oring seal holds.... I will never have to go through the messy process of pealing the cover off. The rtv sealant used on the oem covers is a pain. W/ mag hytec covers they have a drain plug...plus the dipstick and drain plug are very strong magnets that will collect the normal metal particles that are generated over time. The downside is that I paid over $250 each diff cover and $17.99 a qt of royal purple oil. 9 qt total. however iam very pleased w/ it and 2morrow iam installing a fox dual stabilizer kit that ought to look great w/ the cover. BTW.... the rear oil at 50,000 miles was a lil burnt and the front was very clean.

 

p.s. 75w-140 for the rear.... and 75w-90 for the font. If you go royal purple. No stabilizer fluid is required. The synthetic is GL-5 grade.

 

I am interested in the pics, particularly after you get the stabilizers installed. I want to see how the clearance works out.

I'll bet it looks sharp, although I agree it is for appearance more than application. Nothing wrong with that.