Synthetic Gear oil

[LGannon]

Is there any advantage to using a synthetic gear oil in the tranny and final drive over noraml gear oil? I think I read here recently that the tranny appears to run quieter?

[Boffin]

A bit of a religious question that one

 

A lot of people, me included, have had smoother operation from the gearbox using synthetic oil. The UK handbook for my 2004 lists EP90 to GL5 as the only oil for gearbox and final drive. Some people believe that synthetic in the final drive may be instrumental in premature bearing failure. I am not sure one way or the other but will be changing to EP90 in the final drive at the next change (soon).

 

Andy

[LGannon]

Cheers, I think it would be worth the extra few € in the long run. What is EP90 ? the haynes manual says GL5 SAE 80W 90 and I think the synthetic is SAE75W 140, would that be right?

[Boffin]

EP90 is the single weight SAE90 oil, the oils you quote are correct, although the manual only lists the synthetic for the gearbox, not the final drive. As I said, there is a school of thought that the synthetic oil can contribute to the fairly common failure of the final drive bearing. The hypothesis is that the ball bearings slide rather than roll, overloading the bearing cages.

 

Andy

[BMWRich58]

EP90 is the single weight SAE90 oil, the oils you quote are correct, although the manual only lists the synthetic for the gearbox, not the final drive. As I said, there is a school of thought that the synthetic oil can contribute to the fairly common failure of the final drive bearing. The hypothesis is that the ball bearings slide rather than roll, overloading the bearing cages.

 

Andy

 

Can I ask where you have gotten this information??

And are we talking "1100,1150 or the newer 1200 models".

 

I "personally",have yet to have found or heard/read any "negitives" about the rear end synthetic oil usage.

Dealers here State side that I have spoken with, have and use the BMW synth 75w140 in rear ends.

And when I questioned them about "this usage" of this oil in the rear end,I have gotten "No negitive" replys.

[philbytx]

The hypothesis is that the ball bearings slide rather than roll, overloading the bearing cages.

 

Blimey Andy! Now you've done it...I thought this thread had almost died out....

[Lineareagle]

I don't know about the oils. I suspect Andy is correct in his assessment about the 'religiosity' of the issue, but

 

I LOVE THAT AVATAR

[Boffin]

EP90 is the single weight SAE90 oil, the oils you quote are correct, although the manual only lists the synthetic for the gearbox, not the final drive. As I said, there is a school of thought that the synthetic oil can contribute to the fairly common failure of the final drive bearing. The hypothesis is that the ball bearings slide rather than roll, overloading the bearing cages.

 

Andy

 

Can I ask where you have gotten this information??

And are we talking "1100,1150 or the newer 1200 models".

 

I "personally",have yet to have found or heard/read any "negitives" about the rear end synthetic oil usage.

Dealers here State side that I have spoken with, have and use the BMW synth 75w140 in rear ends.

And when I questioned them about "this usage" of this oil in the rear end,I have gotten "No negitive" replys.

 

This came up in discussions on this board a few weeks/months ago. Like I said, it is a hypothesis some people have expressed. The fact that the handbook calls up synth for the gearbox but not the final drive may be a typo, or it may be significant. I see benefit in having smooth shifting from synth in the gearbox but none in the benign environment of the final drive so I am erring on the side of caution. I only give this as a data point - I may well be wrong and am being over-cautious. Finally, as always, YMMV

 

Andy

[ShovelStrokeEd]

I can remember sitting and chatting with the owner of the local HD dealership about oils and the use/application thereof and he spouted the same mantra. Balls/rollers will slide on the more slippery surface rather than rolling causing premature bearing failure. Shouldn't impact the cages at any rate, they are only there to keep the balls spaced around the bearing.

 

I find this difficult to credit, however. What makes the balls turn? Friction, yes? OK, synthetic oil will reduce the friction forces. However, this will only take place if there is no axial load on the bearing. Given that the bearing is designed to support a load, the load will induce some friction within the bearing sufficient to get the balls turning. If the lubrication is sufficiently slippery so that the balls slide rather than roll, it will be sufficiently slippery to prevent any friction from damaging the races. What can and will keep the balls from turning is too high a viscosity oil. You then have a case of the friction of the oil overcoming the friction of the load and this could possibly lead to a bearing failure.

 

I would think that that might be the case where use of 75W140 oil could lead to some problems as the oil will present a higher viscosity at temperature than the 90w oil specified.

 

All of the above is more or less conjecture. Really needs input from bearing and lubrication engineers to support/disprove.

[BMWRich58]

Yes,a very good and understandable point/hypothesis.....thanks to all!!!

 

One question....are there not roller bearings in a transmission?

 

Anyway,based on my experiences with past bikes (BMW) that I've owned,and the bikes of others (BMW),who use the synth 75w140 in their rear gears all including myself would like to report no problems at all with the rear drive components.

Highest mileage BMW bike owned by a friend of mine who uses the synth 75w140 is 135K+. It is a '93K1100LT and believe me,when it comes to maintenence he's very very lax. So that's enough proof for me to continue to use it!

[jackflash]

Is there any advantage to using a synthetic gear oil in the tranny and final drive over noraml gear oil? I think I read here recently that the tranny appears to run quieter?

 

Don't know about your tranny but I had the 600 mile service done on my K1200R last week, and the dealer told me that putting synthetic in the final drive kills the warranty. They put in the BMW recommended semi-synthetic. Better to check it out with BMW than a discussion board in this case. FWIW.

[Jim VonBaden]

Is there any advantage to using a synthetic gear oil in the tranny and final drive over noraml gear oil? I think I read here recently that the tranny appears to run quieter?

 

Don't know about your tranny but I had the 600 mile service done on my K1200R last week, and the dealer told me that putting synthetic in the final drive kills the warranty. They put in the BMW recommended semi-synthetic. Better to check it out with BMW than a discussion board in this case. FWIW.

 

Bunch of stupid dealers out there.

 

Jim

[DavidEBSmith]

Bunch of stupid dealers out there.

 

The service manager at an unnamed dealer once told me that my R1100RT had an electronic speedometer driven off the rear wheel.

[sbouchet]

I use Redline heavey shock proof for the last couple of years in my 2000RT for the trany and the final drive. The final drive runs so cool you can touch it after going for a long ride.

[smiller]

I can remember sitting and chatting with the owner of the local HD dealership about oils and the use/application thereof and he spouted the same mantra. Balls/rollers will slide on the more slippery surface rather than rolling causing premature bearing failure. Shouldn't impact the cages at any rate, they are only there to keep the balls spaced around the bearing.

 

I find this difficult to credit, however. What makes the balls turn? Friction, yes? OK, synthetic oil will reduce the friction forces. However, this will only take place if there is no axial load on the bearing. Given that the bearing is designed to support a load, the load will induce some friction within the bearing sufficient to get the balls turning. If the lubrication is sufficiently slippery so that the balls slide rather than roll, it will be sufficiently slippery to prevent any friction from damaging the races. What can and will keep the balls from turning is too high a viscosity oil. You then have a case of the friction of the oil overcoming the friction of the load and this could possibly lead to a bearing failure.

 

I would think that that might be the case where use of 75W140 oil could lead to some problems as the oil will present a higher viscosity at temperature than the 90w oil specified.

 

All of the above is more or less conjecture. Really needs input from bearing and lubrication engineers to support/disprove.

I agree with you Ed, especially the last sentence. It's amazing how quickly we all sometimes jump on board with a bit of Internet wisdom based on no more evidence than a lot of repetition. I guess it's possible that synthetic oil may present this type of problem, but it seems somewhat doubtful to me and I'd like to see something more than pure conjecture before buying into it.