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Gear oil - Recommended 70W/80 vs 75W/90

  • <i class="fa--xf fal fa-check "><svg xmlns="http://www.w3.org/2000/svg" role="img" aria-hidden="true" ><use href="/data/local/icons/light.svg?v=1721426549#check"></use></svg></i> Discussion starter Discussion starter widu13
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widu13

Active member
Joined
Apr 8, 2024
Messages
220
Location
UK
Bike
2021 R18 TC
Both of these weight oils are GL-5 spec. Has anyone got any experience of running 75W? I can't see that 75W would be much thicker in colder climates and the UK is officially temperate being warmer than both Washington and Maine on similar latitudes as we are warmed by the sea, so we don't get really cold.

Any metallurgists/fluid engineers out there that can definitively state why we couldn't run 75W. At the worst I'm thinking gear selection "may" be clunkier at low temps. 75W/90 is used (at spec) in the R12 series.

Edit:

Interestingly BMW part no. 83222460128 G3 oil is specced for the R12 series as well and 75W/90 is commonly used by BMW dealers instead. I am okay with using this in the final drive (shows on past paperwork), so just need to know opinions on using it in the transmission. I also note that the R12 series were specced with 75W/90 until G3 came on the scene around 2019/2020 and were then specced with G3 using exactly the same mechanical components. Sounds very much like the BM cash machine in action. This is from my 2017 RT - SAF-XO is 75W/90

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Just found this on my 12k service invoice, BMW 75W/90 oil used in the final drive by the Motorrad dealer.

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I got GL5 spec 70/80 Motul from Germany via amazon for just a few dollars more a quart than my go to 75/90 valvoline full synth. It probably doesn’t matter but after having some problems with the bike and BMWNA I went for same/similar to the manual I have/BMW over the counter. It was a much easier change than I thought for the transmission and the final drive was pretty standard difficulty. I bet most shops just dump 75/90 in it. Just change it as recommended or maybe once a year and check both units for metal. Good to go
 
The more and more research that I do and have done, I am convinced that 75W/90 will be a safe and satisfactory substitution. Broadly, 75W/90 (and 140) is factory spec for many vehicles with "sealed for life" gearboxes (dreadful things- difficult to service and NOTHING is maintenance free). Two oil manufacturers cite that 75W/90 is the spec used in locomotion engines. That sounds good to me. In any case I am likely to drop my oil earlier - I do in my cars and other bike. I think I will just crack on and do it. I will only report back if I have difficulty with the gears/drive or it it blows the gears/drive. Of course if I find a benefit I will report that also. I suspect I will not see any difference. I do anything between 6-8k a year on each of my two bikes. My 4 year old Honda NC750S is now on 25k miles, my 6 year old BMW R1200RT LC had 33k miles on when I let it go last week.
 
i think most are gl5 now, synthetic is a good option
changed my rear final drive oil for first service
calls for 210ml
just for shits i measured the oil i got out of the final drive and it was 300ml
i put in 250ml
 
i think most are gl5 now, synthetic is a good option
changed my rear final drive oil for first service
calls for 210ml
just for shits i measured the oil i got out of the final drive and it was 300ml
i put in 250ml
That's almost 50% over spec. that was in there beforehand :eek:
 
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Invoice for R18 or R12 ?
For the R18. Yes I know they've only done two plugs! The previous owner had it done and the dealership told him that the bottom 2 weren't needed. Actually I intend on running my plugs to 24k or more. My Honda has the same plugs and is specced at 36k! The also didn't list the valve check or labour @ £250. I agree, I value my own ability to do servicing. I'm no full blown mechanic/technician, but can do the final drive, wheels off/on, valves etc just basic stuff. I would be lost with an engine rebuild.
 
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About to do a "three hole" change on my bike, and I'm kind of torn on the gear oil. It seems like the cheapest I've found it is $51 a bottle, but when I went to order it..... back ordered for at least a month. The dealer I go to for service quoted 83 DOLLARS A BOTLLE, which isn't happening. Wondering if enough folks have experimented with the 75W90 or even the other synthetic options I've seen mentioned in and around other BMW bikes (Amsoil Severe, Mopar, Land Rover, etc.) to confirm that they haven't had issues after some mileage...

I honestly don't mind ( well I do, but whatever) the $51 or really $153 while under warranty, but the wait/uncertainty makes me kind of want to go in another direction if folks have had success with it.
 
It's bad to go thinner, but ok to go thicker
 
RIF, there are some lengthy threads on the forum for this and all BMW spec'd lubricants. Doesn't seem likely, but perhaps BMW advised shops either weight is acceptable and didn't let customers in on it? Shame on them if the Mother Ship hasn't.

In the US a relatively inexpensive option at the "proper" spec is available at Dodge//Jeep/Chrysler dealerships. My shop buys in bulk and the charge on my bill was within pennies of the "wrong spec" I've used for years v. the "liquid gold" BMW puts in these small bottles that all too many shops are raping customers with. After seeing my bill I did double check the "proper" gear oil had been used because I hadn't been fleeced and was very happy when they confirmed "proper lubricant and reasonable costs".

Not saying I wouldn't use other weight lubricants, but as I despise oil threads in general for their noise to value ratio I'll leave it with less expensive options are available.

YRMV
 
RIF, there are some lengthy threads on the forum for this and all BMW spec'd lubricants. Doesn't seem likely, but perhaps BMW advised shops either weight is acceptable and didn't let customers in on it? Shame on them if the Mother Ship hasn't.

In the US a relatively inexpensive option at the "proper" spec is available at Dodge//Jeep/Chrysler dealerships. My shop buys in bulk and the charge on my bill was within pennies of the "wrong spec" I've used for years v. the "liquid gold" BMW puts in these small bottles that all too many shops are raping customers with. After seeing my bill I did double check the "proper" gear oil had been used because I hadn't been fleeced and was very happy when they confirmed "proper lubricant and reasonable costs".

Not saying I wouldn't use other weight lubricants, but as I despise oil threads in general for their noise to value ratio I'll leave it with less expensive options are available.

YRMV
Yea, I already gave in on engine oil (using the Motul 300v 15W50), and finding that the 70W80 BMW oil is not only expensive but kind of hard to find in the $50 range AND finding that the 75W90 BMW oil seems to be less than "free 2 day shipping" at this point.... Probably just go with a reputable brand of 75W90. I joke with my HD friends about how many features my bike has for the price, but not being able to hop down to one of many dealers and get exactly what I want with tons of aftermarket support is indeed a price to pay.
 
About to do a "three hole" change on my bike, and I'm kind of torn on the gear oil. It seems like the cheapest I've found it is $51 a bottle, but when I went to order it..... back ordered for at least a month. The dealer I go to for service quoted 83 DOLLARS A BOTLLE, which isn't happening. Wondering if enough folks have experimented with the 75W90 or even the other synthetic options I've seen mentioned in and around other BMW bikes (Amsoil Severe, Mopar, Land Rover, etc.) to confirm that they haven't had issues after some mileage...

I honestly don't mind ( well I do, but whatever) the $51 or really $153 while under warranty, but the wait/uncertainty makes me kind of want to go in another direction if folks have had success with it.
My dealer used castrol 75w90 on my bike yesterday. I use 75w90 on my r ninet (did a fair bit of research beforehand)..... it is so obvioisly Ok that one questions it.... anyhow.... I also don't worry about using MA2 spec motor oil either.... since I'm pretty sure there is not a hidden wet clutch in the motor.
 
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