75-90 LS mobile 1 synthetic gear oil in front dif?

[Copperhead]

The Mobil 1 Delvac 75w90 is the best of the Mobil stuff to use for such applications. The same stuff used in commercial applications. None of that limited slip stuff, and a darn good gear lube. My commercial trucks, the differential and transmission OEM's will automatically increase the warranties by 50%... from 500,000 miles to 750,000 miles just by using synthetic in these components. My current semi came with Mobil Delvac 75w90 in the drivetrain from the factory.

 

[Texasmark]

I think GM uses syn or blend in their drive trains. No mention of fluid changes in normal duty ½ ton pickups owners manuals...change intervals.

 

[Copperhead]

True, normal duty GM doesn't have any appreciable recommendation on drive train fluids. I pretty much don't follow what GM says on drive train fluids for my personal vehicles. Every vehicle gets complete drive train fluid changes before 10,000 miles and then every 50,000 miles thereafter. Even with top end full synthetics. My Cadillac to my pickups. Not like having to take out a second mortgage to finance a few quarts of gear lube or trans fluid.

 

[daugen]

My current Kubota dealer changed my front diff lube to 90W, but I'm not sure if it was synthetic.
Kubota dealers, in my experience, seem to be affected by corporate Kubota being at best neutral towards synthetic oil.
Neither my original nor my current dealer stock synthetic motor oil. Hard to believe....they have to special order it for me, and next time I'll just
bring my own. Which they suggested...so that tells me corporate Kubota is not committed to synthetic lube.
So I'm doubting they put synthetic lube in my diffs. maybe the Super UDT2 MHarry referred to. Next time I'm at the dealer, going to ask the service
manager what he did.

Interestingly Ram trucks are the same way, two different Chrysler dealers looked at me a little oddly when I asked for synthetic oil in my truck.
i do know that since putting synthetic oil in my engine, my "hemi tap" at startup is much reduced or gone.
Almost everything I own now has synthetic oil in it, after I break them in on conventional oil.

 

[ray66v]

My current Kubota dealer changed my front diff lube to 90W, but I'm not sure if it was synthetic.
Kubota dealers, in my experience, seem to be affected by corporate Kubota being at best neutral towards synthetic oil.
Neither my original nor my current dealer stock synthetic motor oil. Hard to believe....they have to special order it for me, and next time I'll just
bring my own. Which they suggested...so that tells me corporate Kubota is not committed to synthetic lube.
So I'm doubting they put synthetic lube in my diffs. maybe the Super UDT2 MHarry referred to. Next time I'm at the dealer, going to ask the service
manager what he did.

Interestingly Ram trucks are the same way, two different Chrysler dealers looked at me a little oddly when I asked for synthetic oil in my truck.
i do know that since putting synthetic oil in my engine, my "hemi tap" at startup is much reduced or gone.
Almost everything I own now has synthetic oil in it, after I break them in on conventional oil.

It's not 1980 anymore.

Look up the specs. There is almost no difference between synthetic oil, and mineral oil today.

Lubricity is almost identical, at normal temperatures. That means, your engine will not break in any different with either type of oil.

So is performance. Synthetic oil no longer has any special magic in it. Mineral oil has also evolved, and benefited from the developments of early synthetic oil technology. Again, look up the test data, and compare. There are no significant differences, at normal temperatures.

Synthetic oil, only has an edge, when you are talking extreme temperatures. And, longer drain intervals.

Kubota's failure to embrace synthetic oil, does not seem to be based on science, because there is no down side, except the cost. Which is probably the real reason they are avoiding it.

 

[Texasmark]

Though SUDT, is on the thinner side for viscosity of hydraulic transmission oils, 75-90w, or 80-90w gear oil, is not substantially heavier than hydraulic transmission oil.

It's a popular misconception. But, gear oil is not rated on the same scale.

People think of gear oil as heavy thick oil. Some gear oil is. 80-90w is not like that.

You can see this by doing a pour test. OR, your own timed viscosity test.

They are both about the same viscosity. Both are lightweight GL-4 or better, gear oil. That's why they are interchangeable in many applications.

For reference, at room temperature, 30w motor oil, 80-90w gear oil, and Hydraulic transmission oil, are all about the same viscosity.

The viscosity of a given oil, does vary widely by brand.

The reason gear oil is generally better in a differential is, EP designated gear oil, is designed specifically for applications with hypoid gears. i.e. a differential. This is because, hypoid gears create extreme pressures.

A synthetic EP gear oil is usually ideal.

Viscosity Charts - Bob is the Oil Guy - Bob is the Oil Guy

This is an old post but I was reading it today and want to thank Ray for posting it.

Point of interest to me here is the viscosity chart listed at the bottom of his article. In retrieving Bob's chart, on the right side of Page 1 are several subjects. The one that triggered my response today concerns the use of Molybdenum in today's oils. The Moly Basics article discusses why Moly is very desirable in a lubricant. In reading the other articles I noticed that keeping Moly in suspension for usage in motor oil was a problem that has been solved and is apparently being used in today's oils. The Engine Oil Analysis table shows Moly as a standard item, quantity to be checked in today's oils.....no mention of just what oil uses it, all or just top end, like pure syn, probably depends on mfgr..

In short, this may be another reason why our lubes available today are so much better than before. I'm telling you folks, when I was a kid, 45k miles was a valve job and 100k was a much needed overhaul, with normally 1000 mile oil changes recommended. Today you see normal duty recommended oil changes at 7500 miles, guys on forums talk about their 250k mileage and above, no wrenches on the engine proper, still not using oil and all that. Obviously improvements in metals, manufacturing techniques, cleaner gasoline, and refined lubes have done their job. Sure makes my life easier and less expensive.