Changing rear differential fluid on F250

[Chris B.]

I work at a truck shop and all though I could not tell you every type and brand of HD axels we see we mostly use Mobil 1 75w90 and Schaeffers oils. We do 200-500,000 mile drains no problem with Mobil 1 and every drain is analysis to make sure the oil is working well. By no means am I reccomending you use Mobil 1 over an all ready approved oil that meets all specs I'm just saying that Mobil 1 has prooven to be as HD and protect in HD applications when used.
We are talking about light Ford truck rear end and the M1 75w90 is more then enough for this application.

 

[heyjay]

That is VERY interesting. A truck shop you say?

I buy my Mobil MobilLube SHC 75W-90 by the pail. It works out at $4.25 a quart this way.

The same Mobil distributer also sells Mobil 1 Gear oil 75W-90 and 75W-140, but only in quart bottles. It costs $5.25 a quart.

So why on earth would you put in Mobil 1 Gear Oil when it is NOT approved to Eaton Dana E500 specifications, and costs $1 a quart more?

That really adds to the bill for something like the Eaton Dana HP-40 tandem, and to really put icing on the cake if you ever DO have a warranty claim, your receipts "prove" you've used the wrong oil.

Eaton appears to have a standard response for this: "Too bad, so sad ..."

I think Mobil 1 Gear Oil is great for LS applications. In my GMC LD personal truck, I use it in my rear axle as I have the G80 GovLok "locking" rear axle. Excellent results.

I use MobilLube SHC 75W-90 in my front axle, since my pails have gear pump applicators, so it's very easy to service my front axle. Never use a commercial gear lube in a LS axle as the clutches will slip.

 

[greasezerk]

Use the lube you have now. Any 80/90 weight gl5 lube will work. Stay away from the 140 weight. You probably have a dana 70 might even be a dana 60 if it is a light duty 3/4 ton. look at your gvr to be sure. You should only need 8 oz of modifier. Unless you get it from the dealer you will have to buy 2 7 oz bottles.

 

[Chris B.]

Acctually the shop is at a Wal-Mart DC which services over 500 WM Internationals and also serves many other dedacated trucks. They buy the Mobil 1 in 25-55 gallon drums by the dozzens. We use several different grades depending on the app. and job. All I'm saying is M1 has and will hold up and protect in heavy applications. Some folks like to bad mouth M1 but it is a fine product that is proven. We also Use Schaeffers oils too and always make sure warranty needs are met but I could not tell you by heart what most are, I would have to look it up in the shop.
Doug Hillary is around here some where and he runs M1 is his trucks also, but again I can not tell you what kind they are.

 

[Chris B.]

Sorry Heyjay I didn't mean to say you were bad mouthing M1, just in general it seem to be looked down on. I'll find out what we put in the Hp40's and post back.

 

[heyjay]

No problem Chris.

The last thing I would want to have happen is for you to be denied warranty due to using the wrong gear oil for a commercial application. I've double-checked my Eaton Dana E500 manual and only the Mobil MobilLube SHC 75W-90 is approved for extended warranty and extended drains.

Remember also if you run Eaton LMS hubs, the extended warranty only applies if you use the certified E500 lube.

I see no problem running Mobil 1 Gear Lube in most applications. I use it in the rear axle of my personal 2000 GMC Sierra 1500 4x4. I have no reservations doing this and will continue to do so.

I have the G80 GovLok "locker" and have to use a lube with proper limited-slip additives, and Mobil 1 Gear Oil is such a gear oil. My GovLok works perfectly with Mobil 1 Gear Oil.

Since I have pails of Mobil MobilLube SHC 75W-90 in my shop, I run that in my front axle. It's very easy for me to roll over a pail of SHC and use the gear lube pump to quickly refill my front axle.

However, there IS a difference between Mobil 1 Gear Lube and SHC 75W-90. I'll list the current specs that are different:

Kinematic Viscosity @ 100 C (ASTM D445):
Mobil 1 Gear Lube 75W-90 15.2 cSt
Mobil MobilLube SHC 75W-90 15.9 cSt

Flash Point (ASTM D92):
Mobil 1 Gear Lube 75W-90 175 C / 347 F
Mobil MobilLube SHC 75W-90 205 C / 401 F

Cold Viscosity at -40 C (ASTM D92):
Mobil 1 Gear Lube 75W-90 1,300 Poise
Mobil MobilLube SHC 75W-90 980 Poise

Note: if you live in an extreme cold climate like I do, the "channel point" for gear lubes is 1,500 Poise. Once the ring gear and the ball bearings in the pinion bearing cut a channel through the frozen gear oil, the axle runs dry. First your pinion bearing is destroyed then the ring gear/pinion gear teeth score and fail.

Eaton/Dana 750,000 mile extended warranty?
Mobil 1 Gear Lube 75W-90 NO
Mobil MobilLube SHC 75W-90 Yep

So Mobil 1 Gear Oil is still better than most 75W-90 and 80W-90 conventional GL-5 gear oils. As you can see, the commercial SHC has much better high temp properties and better low temp properties.

If you have several cars/trucks to service at once, and don't have to worry about limited-slip compatibility, a pail or two of SHC 75W-90 will provide superior cold and hot weather protection, and is cheaper to boot.

 

[heyjay]

I'm not bad-mouthing Mobil 1 Gear Oil 75W-90. It works well in "light" trucks and cars.

Mobil makes a dedicated commercial product for the Heavy Trucking industry to meet extended warranties and extended drains on Eaton Dana, Arvin Meritor, and Mack axles.

The Mobil MobilLube SHC 75W-90 is such a product.

According to my Mobil bulk distributer, the Mobil 1 Gear Oil is actually more expensive, even in bulk, due to the additives put in for limited slip service. So why spend more?

According to my Eaton Dana tech rep, I would most certainly void my extended warranties on the HP-40 tandems if I did a fill with Mobil 1 Gear Oil. However, in an emergency I could use it to TOP OFF. Say no more than 2-4 quarts.

I have the Eaton Dana E500 guide in front of me, and there is NO MENTION of approval using Mobil 1 Gear Oil. There is approval with Mobil MobilLube SHC 75W-90.

If I recall, Doug Hillary runs SHC 75W-90 in his tandems and SHC 50 in his RoadRangers. Doug will use Mobil 1 Gear Oil to "top off" if in an emergency in the Outback, say a blown hub seal.

 

[1 FMF]

have a '89 F250, 7.3L here, 130k miles
I drained the fluid out of the rear last summer, it's a wonder the gearcase didn't sieze, the oil was really bad. It was probably the factory fill.
I and am using redline 80w140, and did not add extra limited slip additive. Been running great since. I forget how much I needed for the rear, but I had 7qts total to do both the front and rear differentials. I think the rear took 4 qts, and I used a $3 felpro diff. cover gasket. I don't remember what model rear diff. I have though.
The way I look at it, is if you use a quality syn gear oil, you won't be changing it any time soon, if ever. So I spent the extra few bucks and mail ordered the good stuff. myoilshop is good to get it from and has the best prices on redline.

[ January 23, 2004, 12:49 PM: Message edited by: 1 FMF ]

 

[WVSpaceman]

Royal Purple & Redline both make a full synthetic 75w145 and are available at Jegs and Summit Racing