Shell spirax hd gear oil 85w140

[tonyt2293]

I have a case of this gear oil laying around that I got pretty cheap a few years back to use in my jeep .I have a 02 f350 that calls for synthetic oil. Can't find it anywhere on the packaging if this is synthetic or not anyone know off hand?

 

[GMBoy]

That is most likely a conventional oil. Most of the time heavy duty means conventional oil. In addition if it was synthetic or even semi-syn they would have that on the label for sure for marketing reasons alone.

 

[burbguy82]

It is junk, do not use, I'll dispose of all 12 for you. Send it to me.

Really, I have come to think that the "synthetic" requirement for gear oil is just to have a long drain interval. I have not seen anything that would suggest it is any better than dino, with the exception of life of fluid.

 

[alcyon]

Normally 85W140 is mineral, 75W-140 is syn.
I wouldn't hesitate to use the 85W140.

 

[D60]

Yeah, with your average truck R&P I laugh at the idea of a synthetic requirement. One could argue synthetic is better if they want.

A Ford 10.25/10.5 or Dana 60 front don't care. And in the case of rear axles I don't think wheel bearings care, either.

You've got it. It's paid for. Use it. Get a LubeLocker if you want to swap it out in a few years with less hassle.

 

[ford250]

It’s good stuff

 

[SubieRubyRoo]

It is junk, do not use, I'll dispose of all 12 for you. Send it to me.

Really, I have come to think that the "synthetic" requirement for gear oil is just to have a long drain interval. I have not seen anything that would suggest it is any better than dino, with the exception of life of fluid.

You may think so, and maybe I wanted to believe that as well, but just this morning while researching a comment in my 75w90 thread, I found a paper talking about the choice of base oils when formulating gear oils. The thing that stood out most was:

Operating efficiency by base oil:
Mineral oils (conventional): 60%
PAO/Ester based: 70%
Glycol-based (PAGs): 78%

Not only does that mean better mpg with no other changes to the HTHS or add packs, it also means significantly lower heat generation, which then allows roughly doubling the service life for every 10*F reduction in gear oil temps. If you take both the potential mpg savings combined with longer fluid life (and diff life for that matter), any cost differences from conventional to synthetic are FAR outweighed by overall lifecycle cost, with the PAO/Ester & PAG being potentially magnitudes cheaper depending on use.

If you drive 3k miles per year, that difference may be almost nil because you’d likely sell the vehicle before failure or too many fluid changes. But if you’re an OTR driver or hauling camper trailers from Elkhart IN @ 200k/yr, the cost of synthetics will pale in comparison to the financial benefits of using them.

Not saying the Spirax isn’t good (the 75w90 was tested in my gear oil thread) but it would have to be darn near free and for a low-use vehicle to make sense over a long period of time.

 

[burbguy82]

You may think so, and maybe I wanted to believe that as well, but just this morning while researching a comment in my 75w90 thread, I found a paper talking about the choice of base oils when formulating gear oils. The thing that stood out most was:

Operating efficiency by base oil:
Mineral oils (conventional): 60%
PAO/Ester based: 70%
Glycol-based (PAGs): 78%

Not only does that mean better mpg with no other changes to the HTHS or add packs, it also means significantly lower heat generation, which then allows roughly doubling the service life for every 10*F reduction in gear oil temps. If you take both the potential mpg savings combined with longer fluid life (and diff life for that matter), any cost differences from conventional to synthetic are FAR outweighed by overall lifecycle cost, with the PAO/Ester & PAG being potentially magnitudes cheaper depending on use.

If you drive 3k miles per year, that difference may be almost nil because you’d likely sell the vehicle before failure or too many fluid changes. But if you’re an OTR driver or hauling camper trailers from Elkhart IN @ 200k/yr, the cost of synthetics will pale in comparison to the financial benefits of using them.

Not saying the Spirax isn’t good (the 75w90 was tested in my gear oil thread) but it would have to be darn near free and for a low-use vehicle to make sense over a long period of time.

I have no doubt that the synthetic is "better"...but

One thing that seems to be left out in some of these comparisons is contamination by water. Of course we all dont ford rivers daily, and if you did, synthetic would be a waste as the OCI in the diff decreases to 3k typically. Water intrusion can and does happen, especially in the more humid areas in the form of condensation. Add some of that to the mix and I would venture the numbers would change.

Also, a proper drain and fill can remove damaging stuff out of the equation, like a broken tooth on a spider.......no oil will protect agaist that.

I typically change at 30k-40k, not because I think that the fluid has not done its job, but to drain the contamination, and clean the magnet off......even using a "synthetic" gear oil, not a boutique oil.

Beyond the boutique like HPL Amsoil, RP Redline etc..............are not Mobil1 Valvoline "synthetic" etc a mineral based oil?

I often base my opinions on real world usage than the specs, what happens in usage, rather than a theoretical life. Really, countless people never change the diff oil in a factory car, and how many rear ends do you ever see messed up due to lube, way less than anything else in the drivetrain I would argue.


I did read you post on this subject=very informative.....

https://bobistheoilguy.com/forums/threads/lab-test-results-of-five-75w90-gear-oils.367955/