Rear Drive Lubricant

[Paddler]

I read a prior thread on this topic but can't find it now.  I'm coming up on 12,000 miles on my 2020 R1250RS, so I'll be changing my rear drive lubricant.  There has been some speculation that BMW chooses uncommon lubricants so as to be able to boost their profits.  The 70W-80 GL 5 is one of those uncommon lubricants, available from Mopar through Summit Racing with delayed shipping (September) for ~$30.  Valvoline 75W-90 GL 5 is ~$12 and will be here next Monday.  As my bike is out of warranty I'm not concerned with that issue, and think that because it's a bit higher viscosity shouldn't cause problems of increased wear.  I'll add that I'm strictly a warm weather rider, our last trip we rode in 105F temperatures.

 

Anybody else using 75W 90 GL 5?  I wonder if it could decrease mileage or have other issues?  Why does BMW use 70W-80 GL 5 instead of a more readily available lubricant?  Is the 1250 rear drive unit the same or very similar to previous units that called for 75W-90 GL 5?

[Twisties]

The older bikes took 75w90, and some dealers still use it.  It's what the dealer put in my 1250 that I bought used from them.

[Melty]

Searching for the correct amount of lubricant yields no results. So how much is required? I have a trip planned and will need to service the Final Drive when I return.

[wbw6cos]

180 ml

 

Go to about 2:20 in Brad's video for some his fill technique..

 

 

 

[Paddler]

4 hours ago, Melty said:

Searching for the correct amount of lubricant yields no results. So how much is required? I have a trip planned and will need to service the Final Drive when I return.

I think it's 180ml.

[Skywagon]

180 is correct. Go to beauty supply and get one of these. They are about $5 and has the correct markings on the side

[Claudio]

On 8/2/2023 at 12:52 PM, Paddler said:

Anybody else using 75W 90 GL 5?  I wonder if it could decrease mileage or have other issues?  Why does BMW use 70W-80 GL 5 instead of a more readily available lubricant?  Is the 1250 rear drive unit the same or very similar to previous units that called for 75W-90 GL 5?

I've been using Motul Gear 300 75W90 in my final drive.  Motul's "compatibility" guide indicates it is well suited for the R1250 RT

[Rougarou]

On 8/2/2023 at 1:52 PM, Paddler said:

The 70W-80 GL 5 is one of those uncommon lubricants, available from Mopar

 

Call your local Mopar/Dodge/Chrysler/Jeep dealership.

 

I picked this up via a local dealer, 'twas in stock.

[Paddler]

4 hours ago, Rougarou said:

 

Call your local Mopar/Dodge/Chrysler/Jeep dealership.

 

I picked this up via a local dealer, 'twas in stock.

My local dealership only has it in bulk, not quarts.  The 75W 90 GL-5 Valvoline just arrived. 

[Crumpadump]

I use a 200ml syringe. I bought a 2 pack off Amazon.

[JCtx]

On 8/4/2023 at 8:06 PM, Skywagon said:

180 is correct. Go to beauty supply and get one of these. They are about $5 and has the correct markings on the side

I wouldn't trust those cheapo plastic bottles for accuracy. I used a similar one, and it was off by more than I expected. Since we're talking about just 180mm, you don't want any less than that, especially since a little bit will stay in the bottle for sure. I used a calibrated kitchen measurement my wife has, and marked the bottle accordingly (which was almost on the 190-ml mark there).

 

Finally, I use Castrol Syntrax 75/90 long life, which is supposedly what BMW used before they came up with their own fluids. I changed it with the first oil change, to get all the assembly and break-in crap out of there. And fluid was nasty (did 2 'flushes'). I changed it again with the 2nd oil change, and it still wasn't quite clear. I will change it again at next oil change, and expect it to come out mostly clear.

[Skywagon]

16 minutes ago, JCtx said:

wouldn't trust those cheapo plastic bottles for accuracy

Guess I’ve been doing it wrong for 25 years of BMW ownership, even though it matches exactly to the medical grade syringe my cardio Dr gave me. 

[dirtrider]

12 hours ago, Skywagon said:

Guess I’ve been doing it wrong for 25 years of BMW ownership, even though it matches exactly to the medical grade syringe my cardio Dr gave me. 

Morning David

 

There is most likely more clinging gear oil left in the final drive cavity after dropping the cold gear oil than the inaccuracy of most marked containers. 

 

Think the dealer uses anything that reads to the tenth or hundredth? They are probably lucky to get it within an ounce & they usually don't allow it to drain long enough to get most of the old cold gear oil out.  

 

If anybody wants to go anal then just clean the container out, then put the empty container on a good digital scale & zero the scale with the empty container. Then pour 70°f  water in until the scale reads  6.35 ounces or 180.0 grams. 

 

 

Personally I just use an 8 ounce plastic bottle with a line scribed around it's OD at the 180 milliliter level. 

 

I pay more attention to getting as much old gear oil out as possible (usually an overnight drain if time allows) than putting exactly 180 milliliters back in. 

 

 

[Paddler]

Why didn't BMW design the bottom edge of the filler hole level with the amount of lubricant required with the bike on level ground?  Everybody else does.

[dirtrider]

14 minutes ago, Paddler said:

Why didn't BMW design the bottom edge of the filler hole level with the amount of lubricant required with the bike on level ground?  Everybody else does.

Afternoon Paddler

 

You would have to ask BMW for their intent but my educated guess would be a clearance and/or access issue.

 

The BMW final drive is so compact that it basically hugs the large ring gear so there isn't much room inside the final drive cavity. The BMW drive holds so little fluid that the actual fluid level is slightly below the axle center line so you would basically be trying to fill uphill into a hole. That might not be so bad if you could get a hose in there then pointed down but the ring gear is so close there probably isn't enough clearance to allow that. 

 

Plus, most motor companies do not design for service, their number one goal is to design for assembly. BMW surely doesn't design for do-it-yourselfers & dealers have no problems with the current filling method.  

 

It's not a big deal,  just pour 180 milliliters of gear oil into a container,  then dump it in, done deal with no adding a little then keep looking adding more & looking again until it's to the correct level.  

[wbw6cos]

6 hours ago, dirtrider said:

 

 

I pay more attention to getting as much old gear oil out as possible (usually an overnight drain if time allows) than putting exactly 180 milliliters back in. 

 

 

 

 

Greetings dirtrider,

 

Out of curiosity,  do you measure the amount that drains out?

 

Thanks!

[Paddler]

On my Mercury outboard the procedure is to drain the fluid, connect a threaded hose into the drain hole, pump fluid in until it comes out of the upper hole, install the upper plug, then disconnect filler hose and install tha drain plug.  No need to measure anything.  But you need to remove the prop, and installing the drain plug while the lubricant wants to drain out can be messy.  Measuring is probably easier.

[dirtrider]

10 minutes ago, wbw6cos said:

 

 

Greetings dirtrider,

 

Out of curiosity,  do you measure the amount that drains out?

 

Thanks!

Afternoon wbw6cos

 

No, but as long as it looks like about 6 ounces of gear oil drained out then I'm happy. 

 

On my old 1150GS, before I extended the final drive vent to up under the seat, sometimes I would see some water come out before the gear oil.   

[JCtx]

On 8/21/2023 at 5:33 AM, dirtrider said:

put the empty container on a good digital scale & zero the scale with the empty container. Then pour 70°f  water in until the scale reads  6.35 ounces or 180.0 grams.

That's what I did, after 3 different graduated kitchen measuring cups my wife had were all over the place. Ha ha. Turns out the cheap graduated plastic containers (with a spout) I bought from Amazon were the worst by far, showing like 190+ ml for 180. If I had trusted the container, it'd had been under-filled. I personally think the 180 is calculated not fully draining the FD for hours, like many of us do, since no service department does that. So it's imperative to make sure you're actually putting 180ml when draining it for hours, which is what I did, since fluid was nasty. Since almost none of us run our bikes to top speed, I'd assume it's better to be a little bit over than under filled, since our FDs are now vented, but who knows. I'm doing it accurately, and leaving the bottle upside down for 10 minutes, until no more seems to flow out into the FD, just leaving a tiny bit in there.

[dirtrider]

2 hours ago, JCtx said:

That's what I did, after 3 different graduated kitchen measuring cups my wife had were all over the place. Ha ha. Turns out the cheap graduated plastic containers (with a spout) I bought from Amazon were the worst by far, showing like 190+ ml for 180. If I had trusted the container, it'd had been under-filled. I personally think the 180 is calculated not fully draining the FD for hours, like many of us do, since no service department does that. So it's imperative to make sure you're actually putting 180ml when draining it for hours, which is what I did, since fluid was nasty. Since almost none of us run our bikes to top speed, I'd assume it's better to be a little bit over than under filled, since our FDs are now vented, but who knows. I'm doing it accurately, and leaving the bottle upside down for 10 minutes, until no more seems to flow out into the FD, just leaving a tiny bit in there.

Afternoon JCtx

 

The initial fill (not the after-change fill) on the Wethead is 200 Milliliters, I'm not sure what the initial on the Shiftcam is but probably about the same.   

 

In any case, that is only 20  Milliliters (about .67 ounces) difference, there is no way an overnight drain will get "all" the gear oil out so even on an overnight drain it is probably way less than 1/4 ounce difference. 

[JCtx]

Hey, thank you for that 200ml info; I'm sure it's the same for shiftcams, since the FDs are identical (basically just the engine changed). And you're correct that you cannot drain everything overnight, especially that heavy and sticky fluid... BUT, my point was we drain more than a dealer draining it for 10 minutes. And same thing with the oil: I drain it until nothing comes out, and always end up having to put a little more than what the manual says (to the top mark). Anyway, I think it's perfectly fine to just put 180ml in there, regardless how long we drain the old fluid... BUT, make sure it's actually 180ml. So I suggest everybody checks their amount by the very clever 'test' you listed (with 180g of water), because most of those graduated containers are not calibrated... and most read high, at least the several I tried.

[Skywagon]

On 8/21/2023 at 12:43 PM, Paddler said:

installing the drain plug while the lubricant wants to drain out can be messy

put the vent plug back in before you disconnect from the bottom fill hole. You won’t lose more than a drop or two. I change mine often to make sure no salt water. 

[Paddler]

1 hour ago, Skywagon said:

put the vent plug back in before you disconnect from the bottom fill hole. You won’t lose more than a drop or two. I change mine often to make sure no salt water. 

That's what I've always done.  Still a little bit of fluid leaks out, depending how quick one is.

[Hosstage]

5 hours ago, Paddler said:

That's what I've always done.  Still a little bit of fluid leaks out, depending how quick one is.

It does, but very little. Definitely not worth fretting about.

[Dave_in_TX]

On 8/21/2023 at 12:08 PM, Paddler said:

Why didn't BMW design the bottom edge of the filler hole level with the amount of lubricant required with the bike on level ground?  Everybody else does.

That same final drive is used on multiple models. The position of the hole may vary between models of vary between standard or low suspension.