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Diff oil change

45675 Views 28 Replies 15 Participants Last post by  JimP
hello all, just doing the first service on my kodiak, and upon draining the rear diff oil i noticed i loosened the drain bolt further up towards the engine(not the engine, its still on the rear diff) and theres another drain bolt right under the back of the diff where the axles go into the housing, did i just drain something different than diff oil or does the rear diff just have 2 drain plugs? thanks and sorry for the dumb question. Im use to working on old junk bikes lol
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You're in no danger to drain other fluid back there. It's all coming from the final drive. The one closer to the front is the right drain plug for changing the oil on the final drive as stated in the service manual, I don't really know what is the purpose for the other plug, it may be a partial drain since is at a higher level than the front plug. Or a backup since I heard that the allen heads on those drain plugs strip out easily...?
i had the same question thats why im on this forum lol.... my next question would be what did ya fill it with? i used the same diff fluid i used in the front think i need to drain it again and use something different?
i had the same question thats why im on this forum lol.... my next question would be what did ya fill it with? i used the same diff fluid i used in the front think i need to drain it again and use something different?
I used the Yamaha recommended Mobilfluid 424 , takes about 1/2 liter. I only found it in 2.5 Gal jug , so I'm set for a long time with that fluid lol
dealer gave me amsoil synthetic atv-utv transmission & Differential fluid
13$ quart
to use in both front and rear
Not sure why they would do that, from what I understand they are two different oils from and rear
There are indeed two different oils required for the diffs.
Odd . . . the dealer also gave me the same diff oil for the front and rear diffs.
Doing a little bit of searching turned up this on the Moblfluid 424 that is suppose to be used for the final gear lube:

Car Parts & Maintenance
Engine Oil
Q: What is the oil equivalent to Mobil 424?
A: Quick Answer
Some equivalent products to Mobilfluid 424 include Chevron 1000 THF, 76 Hydraulic Tractor Fluid, BlueSky Terra Multi-Trac THF and Kendall Hyken 052 Farm Tractor Lubricant. Mobilfluid 424 and equivalent products work with applications requiring API GL-4 or SAE 80W grade lubricants in all gear applications except hypoid gear designs.
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Full Answer

Mobilfluid 424 hydraulic oil is a high-performance multipurpose tractor lubricant designed for agricultural and commercial tractors. ExxonMobil recommends Mobilfluid 424 for commercial transmission applications that require Type A, Dexron and Type F fluids only. Some of its benefits include optimized clutch and PTO performance, consistent operating response, extended seal life and reduced wear and maintenance costs.

So you should not be able to use the same oil for the Final Gear Oil and the Differential Oil since according to the manual the Differential Oil should be SAE 80 API GL-4 Hypoid Gear Oil because of the disclaimer that I have highlighted in red in the above.

Now will it work, quite possibly but I would like the correct oil in what ever I am running it in.

A big problem as I now see it is finding a place that sells MobllFluid 424 in a quart bottle instead of 5gallons+

Perhaps that is why the dealer is dolling out the SAE 80 API GL-4 oil
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I found it in 2.5 gal container here:

It will last a loooong time since a fluid change only takes about a half quart
At that price I think that I search out a cheaper fluid to use as a replacement.

From what I have found on line and doing searches on what to use it look like there are a number of fluids out there that will work quite well. You just have to make sure that it has the friction modifier in it for the wet brake along with carrying a GL-5 rating. I have't checked with my local shop to see just what they use yet or if they might have smaller containers of the Mobilfluid 424 yet.
I've heard of a few people using Travellers Hydraulic Fluid, funnily enough the same stuff we use in our tractors, I've yet to use it in my Kodi though, I'll leave that to the more ballsy people.
I guess it's worth some research if you're looking for a substitute.
Mobil 424 is essentially just tractor hydraulic fluid.
I found that Yamaha does bottle a fluid for the final drive. It is:

Yamalube Friction-Modified Shaft Drive Gear Oil and it comes in a quart bottle. When you figure out the price + shipping it is more expensive than the price of Moblefluid 424 in a 2.5 gallon jug. But then you won't have 2 gallons in a open container sitting around for the next 10 years.

Yes, yamalube friction modified plus shaft drive oil is shat you are supposed to use for the rear final drive. For the front diff, you can use the same stuff, or use gear oil, although there is really no point in it because a single quart of friction modified plus is plenty to fill up both diffs. If you do not want to drive all the way to your Yamaha dealer than you can buy it and have it shipped to your door from yamahapartshouse.com (Babbitts Yamaha)
How do i know how much oil to put in front diff of 18 kodiak 450 is it a guessing game theres only a fill hole around quarter
Look at your owners manual, it will give you the capacity, it will be under specifications.

A quarter of a quart sounds about right
My book clearly says 80 Hypoid gear oil for the differential, that is a long way from Mobil 424 specs. That is how I see it, am I wrong?
Correct for the front diff SAE 80 API GL-4 Hypoid Gear oil. Most gear oils will meet that GL-4 specifications and that is the main spec that you want to make sure of.

It is the rear diff or final gear oil that you need to be careful with and that is where Mobil 423 specs come in at. It needs to meet the GL-5 which should have the friction modifier in it for the wet brake.
That is all interesting, I knew they were different, but had not looked carefully. Thanks for the input!
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