My apologies - ADOT

[Semper Gumby]

Hi Guys,

Well I can no longer get the gear oil I like.  No store stocks it anymore.

In talking with Valvoline, they are telling me that Valvoline Syncromesh MTL yellow metal safe from corrosion.  I suspect that none of you are using this synthetic GL-4 product or have even heard of it.

At 132,000 miles I’m wondering what to use next in this continued experiment in longevity.   

Thanks in advance.   8-)

[Bob_Roller]

I've been using BMW branded gear oil for about 35 years .

I know that least at one time, Spectro Oils was the manufacturer, don't know if they still are .

90,000 miles (145,000 km ) of use on the '81 R65 and 70,000 miles ( 113,000 km ) on the oilhead, no issues yet .

[Semper Gumby]

Hi Bob.

I’m leary of using synthetic products due to seal incompatibility on my old boiks. But i need to find something.  I suspect it’s my changing things twice a year that is making my gearbox last so long....  [smiley=2vrolijk_08.gif]

[Bob_Roller]

I found a bottle of BMW gear oil in the garage .

No mention of Spectro Oils as the manfacturer .

It's a ' blend ', so I think it may contain semi-synthetic / synthetic oils .

It states on the bottle, that it is for use in Boxer gearboxes, shaft and final drives .

My final drive output seal finally started seeping about three years ago, 88,000 miles .

When I disassembled the final drive to replace the seal, I closely inspected the brass parts to see if the oil had caused problems and I found no issues .

[Barry]

I've not had any problems using full synthetic in the gearbox, shaft and final drive.


Interesting that Valvoline are talking about a synchromesh MTL GL4 oil.  Two things come to mind:

It will contain friction modifiers to make the synchros work properly and added friction is not something I'd be looking for.

It's a GL4 when BMW recommend GL5.   I'd be fairly laid back about this as the only difference between GL4 and GL5 is the amount rather than type of anti wear additives.  There is nothing about an airhead transmission system that should need GL5 in the first place as we have a spiral bevel rather than hypoid rear drive and in general the GL5 spec was not intended for gearboxes.

[Bob_Roller]

The BMW oil is GL5 .

Semper G, my '81 R65 was assembled in 09/80 and your bike is an '80 model year bike, i don't think there are any differences in the final drives on our bikes .

[Semper Gumby]

Hi Barry,

I didn’t realize that’s what “friction modifiers” were.  The oil seems awfully thin on the highly subjective shake the bottle test.  But it does say on the bottle approved for yellow metals.

Bob,

Your bike should have the first square rear end.  Mine used to be the round type but I have changed it and put on the LS wheel to match the k100rs front end I have on the bike now.

I’m in a quandary.  It’s a BMW/BSA thing of mine own making.

[Semper Gumby]

I’m thinking Motul MOTYLGEAR 75w90.  The tech data sheet says good for all yellow metal designs Gl-4 spec and also GL-5.  I think this covers both my bikes...

https://s3-eu-west-1.amazonaws.com/motul-production2/images/product_descriptions/technical_data_sheets/144/Motylgear_75W-90__28GB_29.pdf?1492016031

[Barry]

Manual transmission fluids are very thin these days so the Valvoline MTF would have been something like a 75W80 or 75W85 at best.

The Motul looks much better but any 75W90 synthetic should do.

My understanding of the yellow metal issue is it's no longer a problem with any of the modern gear oils except for brass synchronizers which airheads don't have.

Here's a very good overview of gear oils http://www.widman.biz/uploads/Transaxle_oil.pdf

[mrclubike]

GL-4 is for use with synchronizes
We need GL-5
Any good quality GL-5 75W90 or 80W90 will do 

[Semper Gumby]

Barry - now that I think of it, I may still try the Valvoline Syncromesh but in the chain case of a BSA.   There are some yellow metal bits in there and the friction modifiers might be just the thing for not wrecking the clutch.

Right now I’m trying amsoil sythetic chaincase fluid in one of the BSAs.  So far so good.  Motul on order for the gearbox drive shaft and rear diff on the R65.  My local shop doesn’t carry it and the guy behind the desk said “just order it off amazon”.

Well ok then.....

[Semper Gumby]

GL-4 is for use with synchronizes
We need GL-5
Any good quality GL-5 75W90 or 80W90 will do 

Perhaps I will go back to the Valvoline White bottle 80w90 GL-5 on the R65 and try the Motul in the BSA boxes that has the bronze bushings.  I guess one size is not going to fit all. 

Thanks for all the input guys.

[Tony Smith]

Made me wonder what is currently in my BMWs - relevant since it is almost time for the yearly oil change for all final drives, shafts and gearboxes.

I looked and from the near empty status of the 5lt drum I'm confident that the two airheads currently have Nulon SAe90 Limitied slip differential oil (GL-5) in them.

What goes in next month will be determined by the cheapest EP 90w oil that meets GL-4 or GL-5. I'm not aware of any yellow metal in an airhead that would be in any danger from non-compliant oil.