Finally found 85/140 Mobil 1

[Gbenzx01]

without having to buy 5gal pail.
It was at a fleet service garage & I was told abt them by the mobil distrb after they realized I was not going to pay the price for 5gal.
I really needed 6.2qts to fill the rear of the jeep cherokee & the Dmax but they said they could only spare 1gal.
Was only going to chg us $10 but gave him $25 anyway knowing what the stuff cost! At the sound of 1hr labor @ $45 to put it in for each truck we opted to doit ourselves.
For what reason can one imagine does mobil be so stingy with this gear oil(no qts or gal) when there are millions I thimk that can use it in these types of vehicles?
Now if I fill the jeep with 2qts that leaves only 2qts for the Dmax. Sense the Dmax was just chgd abt 5k ago(mobil 75/90) I thimk we'll just drain enough to add 2qts & let it be till 25k interval.
Does that make sense? Same base oil?
Yes I know, have to pay the toll down the road but the jerks won't get my $200+ until I have too.
Could have used a different brand but this can be a prob if someone adds wrong stuff to the wrong end.
The 75/90 done a good job(not getting too hot) but just tobe on the safe side wanted to make the chg. Anyone mixed this stuff?

Thanx Gben

[Kennedy]

Why so heavy? The std 75/80w90 is more than adequate. I'd expect a decline in fuel economy based on a conversation with George M about this very topic.

[george morrison]

To reiterate John Kennedy's response: Every 80,000 pound tractor/trailer you pass on the interstates is running Mobil 1 75W-90 gear oil in their rear ends.. 85W-140 is simply waaay too thick for our Duramax rear. Simply not needed. It robs horsepower, creates additional heat in the summertime and will not provide any increased level of performance in our application.
This is the classic case where if 2 asperins are good, four asperins are NOT better...
Jeep and some other brands that shall remain nameless, prescribe 80W-140 to cover for a very overloaded/under designed final.. Our Duramax is not. We need to optimize our lubricant viscosities and Mobil 1 75W-90 is that lubricant.
This is why Mobil does not package it in anything smaller than 5 gallon pails or 55 gallon drums. It is primarily recommended for off-highway applications where a maximum speed of 35 mph would be encountered, hauling waaaayy overloaded in extreme conditions..
George Morrison, STLE CLS

[Gbenzx01]

Well John,

we're basing this on what we've experienced so far & what they recommend in their manual.
Just north of Helen Ga it's a pretty good climb with my son's big 5th upto the parking lot at the Appalachin Trail.
This is the 3rd trip we've pulled over up there to chk the diff by feel. After cooling for abt 1/2 minute after stopping we can lay a hand on the diff cover w/o burning.
Now as the unfaithful tin stroke gas station Dudge is towed off unto the sunset the Dmax istobe called upon for double duty into the hill country. I could say numbers but you know how that is around here so thimk heavy will suffice.
Also, most of the hotshots we've come across use the 130 or 140 except Broker of course, 110wt with a cooling contraption.
Also, went back to your site 2-3 times thinking you would have it. That's all. :confused:

Thnx John, Gben

[Gbenzx01]

George,

you must have punched send while I was still pecking.
But we still run a couple otr's & that's exactly what we continue to use in those finals with no probs ever.
I may then just leave well enough alone for now but ohno not another guage!

Thanx Guys, Gben

[JimWilson]

I don't think the oil is too heavy, or completely unnecessary either. That weight is listed for someone who tows a lot or pulls something that's heavy. Living in a warm climate, and towing a large trailer, I don't see where it will cause you any problems.

I also don't see how a thicker oil in the rear diff will noticeably affect gas mileage. Heck, even if you switched to 10w40 in the engine I can't see it making any difference at the pump.

[Gbenzx01]

JimWilson,

I guess it is the 500+lbs torque & 10-15 tons against the tiny diff with 4 little qts at 5mph on the side of these stairsteps we've been climbing in the smokies bugging us.
We're used to GALLONS in our heavy stuff & not quarts & pints. If one can keep the speed up the thing has better cooling but not so where we go.
I was also told this am that I'm checking diff heat in the wrong place. A man with about 20 otr's
been in the business longer than us says to chk at the bottom of the hill after abt 1/2hr of the allison braking against it.
We've burned a couple rear diff's in other brands of trucks & we know how to do it. So now just trying tobe sure not todoit.
Anyone with a diff temp guage & know what it is saying under these conditions?
Now if we could just teach the Dmax to stay in Fla. ;)

Thanx Jim, Gben

[chevmeister]

Gben ever think of getitng the Mag-Hytek. If your so hard on your rear 7-8 quarts instead of 4 should help. plus you would have the option of installing a gauge to monitor temp. Just a suggestion.

[Gbenzx01]

chevmeister,

I checked upon the diff cover you speak of & turns out that it is $238 which is abt $20 more than the 5gals of Mobil 1.
But as both John & George has herein implied don't believe our configuration is a very serious concern.
Like anyone else our awareness is always limited by knowledge gained.
Broker, if I may related to getting only 85k mi from the bearings & 130-150k mi before rebuild.
They're 1 tons using 110wt, 8qt cap & cooling fan setup. His operation with the Heavy loads pulling autos across the land probly taps beyond the limits of these trucks at times.
With 40+ yrs exp with synthetic oils we have a great deal of respect for them. Not blends or socalled synthetics containing petro via some judge someplace.
May yet install a guage just for our own curiosity tho to see if the temp gets above say 220-240 or so with the 75/90.

Thanx chevmeister,

Gben

[ 01-24-2004, 01:39 AM: Message edited by: Gbenzx01 ]