can someone explain how the wildly different gearbox oil specs make sense?

T'was early on a rainy Saturday morning, and I was doing some light reading in the 2022 Ryker Operators Guide. Interesting reading, but then things get weird and it turns out to be a mystery story! There, on page 119, I discover a plot twist/puzzle/conundrum! As you can see in the attached image, the lubricant specs for the gearbox suggest two very different options for warm temperature operation: 10W50 synth motor oil, OR 75W140 synth gear oil:shocked:

So, can anyone advise on how these two very different lubricants can be deemed interchangeable by BRP?

And...I wanted to add a poll, but couldn't figure out how to do so. If someone can add a poll to this thread as to which option you will, or have chosen, that would be fun.

PS - I'll go with 75W140 synth gear oil when the time comes

Now that is a very interesting oil combination. Al though I don't own a Ryker myself I would love to hear the explanation for that myself.

:shocked: I'd guess that the BRP Proof-Readers have done it again :rolleyes: and let yet another messed up cut-&-paste job slip through the thorough cursory glance they check every manual with!! :gaah: :banghead:

:roflblack::roflblack::banghead:

What’s interesting is the Rykers manual calls out engine oil AND gear box oil. The gear box doesn’t have a dip stick but rather a level plug. So the engine oil is separate from the gear box oil?

Engine oil.

Gear Box

The confusion comes from thinking the 2 oil grades are apples and apples. Which they are not. The viscosities given by BRP are similar in function. It would be nice if BRP would define "Warm Temperatures". If I had to guess I'd say 85~90 degrees Fahrenheit (around 30 Celsius) would qualify as 'Warm' for lubrication purposes.

These 2 charts should help to clarify. (The temperature chart is in Celsius, so you'll have to convert) The 2nd aspect is that gear oil stands up to heat better than motor oil when you are talking about the crushing action of gears as opposed to engine components which do not present the same kind of forces. This explains the switch from Engine Motor Oil to Gear Oil in BRP's recommendations.

In this 1st Chart. Compare the SAE Auto to the SAE Gear to compare functional viscosities. You'll see the numbers do not correlate to what you might assume.


Heat tends to thin just about any liquid. So, to achieve the desired viscosity when hot. You have to increase viscosity as heat increases.


I went with Amsoil 75/140 in our Ryker. The gear oil will be thicker in cold weather. But if you're ever riding in warm weather. I think Gear Oil will do a better job. You might lose a bit of HP and fuel mileage in cold weather. But I think this will be negligible.

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Originally Posted by BajaRon

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In this 1st Chart. Compare the SAE Auto to the SAE Gear to compare functional viscosities. You'll see the numbers do not correlate to what you might assume. ......

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I remember a Detroit or Cummins instructor giving an explanation about the 2 differing standards but can't remember it right now. It was more than just 2 different committees setting the standard.

Don't forget the final drive oil also.

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Originally Posted by peacons

Don't forget the final drive oil also.

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Rather a non sequitur, but in case anyone is wondering...no weirdness in the specs.

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Originally Posted by AreWeNotMen

Rather a non sequitur, but in case anyone is wondering...no weirdness in the specs.

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This is because the final drive uses a hypoid gear set. Very particular about what lubricant to use and requires a gear oil. We cheated and used the same 75/140 in both drives on our own Ryker.

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Originally Posted by BajaRon

This is because the final drive uses a hypoid gear set. Very particular about what lubricant to use and requires a gear oil. We cheated and used the same 75/140 in both drives on our own Ryker.

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That's what I intend to do also!

Thanks for your insights on this topic BajaRon.

Ok, I am confused. But I thought a Ryker had a belt driven CVT and does not require gear oil.
Or are you referring to the differential?

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Originally Posted by Raven

Ok, I am confused. But I thought a Ryker had a belt driven CVT and does not require gear oil.
Or are you referring to the differential?

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The 'Final Drive' they are referring to is the gearset on the end of the shaft drive that turns the longitudinal shaft rotation thru 90° into wheel rotation, where a differential would be IF the Ryker had 2 rear wheels, but it doesn't. ;)

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Originally Posted by Raven

Ok, I am confused. But I thought a Ryker had a belt driven CVT and does not require gear oil.
Or are you referring to the differential?

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No, it has a CVT AND a gearbox (which allows the basic gear selection: Forward - Neutral -Reverse). My original post was indeed about the Ryker gearbox and the seemingly weird oil options...I later added a comment about the final drive oil (noting that it didn't have weird options)

Thank you that is what I was asking about.
Wasn't thinking of the forward and reverse.

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Originally Posted by Peter Aawen

The 'Final Drive' they are referring to is the gearset on the end of the shaft drive that turns the longitudinal shaft rotation thru 90° into wheel rotation, where a differential would be IF the Ryker had 2 rear wheels, but it doesn't. ;)

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Awesome! I love the big words and technical explanation! ;-)

BRP should hire you to write their manuals! It might help to alleviate the current confusion.