Trans and Final Drive Lubricant Sanity Check

[kinchy]

I have BMW 75W140 synthetic in the garage. This lube works in both the trans and final drive correct?

[Glacier_g_rt]

75-90 for final drive and 75-140 for gear box (transmission) is what I've been using for the last 40K miles on my '96 and '00 RT's. I typically ride 7k per season and change all of the fluids every spring

before the season starts. I've never had an issue with lubrication on either bike. For what it's worth.

[Glacier_g_rt]

In the MC FAQ section under They All Do That 'transmission issues' they refer to using 75W-140 Full Synthetic for quieting the gear box.

 

"Bill bedgood@peoplepc.com Looked up the spec in the Haynes just to be sure: �the Haynes manual calls for Hypoid gear oil, API class GL5, SAE 90 above 5 degrees C, SAE 80 below 5 degrees C, or SAE 80w 90 for all conditions. Matt says the �75W140 is a synthetic gear oil. BMW sells it under their own label. About $12.00 a quart. Only takes about a quart to change the fluids in the tranny and final drive. It does make a difference. Unlike changing to synthetic engine oil you can make the switch to the synthetic. gear oil anytime."

 

The above almost implies that you can use the 75W-140 in the final drive as well as the gear box. Personally I would check with the dealer before using it in the final drive. Seems heavier than necessary for the smaller gears. IMO.

 

[kinchy]

Thanks gentlemen

[philbytx]

I wouldn't use 75w140 in the FD. I use it in the gearbox of both bikes as BMW does spec it for them.

Now, this is NOT definitive but the heavier weight oil IS on a list of FD failure suspects....stick with 75w90 in the FD.

 

[wibeem]

I'd listen to Phil solely based on the other advice he's given me

 

But for what it's worth, my local BMW dealer gave me 75w140 when I told them I had recently acquired a 2000 R1100RT and wanted to change the lubricant in the transmission and final drive. I've heard subsequently that because it's the super synthetic it can (or should) be heavier weight. Don't know if there's any truth to that. I've only put about 500 miles on since. No issues, but now I'm wondering if I should drain the FD and change back to 75w90 or just wait for the next change.

[DavidEBSmith]

The 75w140 controversy is this:

 

- The manuals say 80w90 and don't say 75w140.

 

- Nobody knows if this is because 75w140 wasn't available at the time the manuals were printed, because BMW hasn't tested it to see if it's OK, or because BMW has tested it and found it deficient.

 

- Nobody knows the cause of the excessive final drive failures.

 

- You can imagine that the 75w140 would stick to the gears more, or less, or would lubricate the bearings more, or less, and that might cause something to happen. But nobody knows for sure.

 

- BMW dealers are putting 75w140 in final drives without a second thought.

 

For what it's worth, I used 80w90 for a while, then I used 75w140 for a while, then I switched back to 80w90 for a while, and I have no idea what's in the bike now. 192K miles on the final drive, except for the big bearing. The big bearing went 130K miles with no problems before I changed it just to be sure, and is up to 62K miles since.

[Boffin]

The 75w140 controversy is this:

 

- The manuals say 80w90 and don't say 75w140.

 

- Nobody knows if this is because 75w140 wasn't available at the time the manuals were printed, because BMW hasn't tested it to see if it's OK, or because BMW has tested it and found it deficient.

 

- Nobody knows the cause of the excessive final drive failures.

 

 

 

My manual says either 80W90 or 75W140 for the gearbox (transmission) but only says 80W90 for the final drive. This implies that there is a reason to not use 75W140 in the FD.

 

As for BMW dealers... they are not the factory nor mechanical design engineers, I would not use them as a reason to override what the manual says without a technical bulletin.

 

Andy

[Trullion]

 

My manual says either 80W90 or 75W140 for the gearbox (transmission) but only says 80W90 for the final drive. This implies that there is a reason to not use 75W140 in the FD.

 

Equally the manual implies that there is no reason to use 75W/140 in the FD. This oil is much more expensive than the 80W/90 specified in the manual (which may be why BMW stealers use it) and exceeds the required spec. I use ordinary 80W/90 grade in the FDs of both my oilheads without any problems so far. Not sure that BMW always knows best anyway. If they do, how come the earlier 1200s had 'sealed for life' lubrication for the FDs, then lo and behold a few years later they put a drain plug in them?

 

Just my opinion; what oil to use always generates loads of these.

[Jerry Duke]

I've used exclusively Mobile 1 synthetic 75W90 in both transmission and FD in my last two oilheads. Both went over 100,000 miles.

Like DavidEBSmith, I change all fluids every year.

[philbytx]

For all the tight wadded BMW owners on the site!

You may be interested to know that WallyWorld Supertech 75w140 synthetic is manufactured by Mobil. No coupons to cut, just a little "generic" version available for a few bucks less at your local store

[Glacier_g_rt]

Thanks for clarification on this issue guys. Experimentation can be expensive for sure so it's always a good ask. It's free here anyway.