Synthetic Gear Lube

[Justin B.]

This info probably won't be much good to our friends across the pond, unless they have a neighborhood Wally-World (Wal-Mart)! 

I was needing to change the lube in the final drive, drive-shaft, and tranny in my R100 so I poked around on bobistheoilguy.com and saw some discussion about Supertech synthetic gear lubes being safe for copper and brass.  I ordered some and it got here yesterday and the label proclaimed it protected brass and copper.  It was several dollars a quart less than the name brand stuff so I figured it might be a good deal.

This stuff is made by Warren Performance Products and is supposed to be the same formulation as their MAG1 lube except private labelled for Wal-Mart.  The stuff smells a lot better than most gear lubes and was almost clear.

The drain plug in my trans had a minor about of "fuzz" on the magnet and the final drive had quite a bit of fuzz but no chunks.

[Bob_Roller]

I've been looking for gear lube the last week .

I had both tires replaced at the local BMW dealer for my oilhead, believe it or not, they were in line price wise for tires, mounting and balancing, with online sites and independent bike shop labor prices .

I looked for the usual BMW gear oil that I have been using for around 35 years, they no longer stock it, only synthetic gear lube at $19US per quart .

I was thinking of going back to Castrol gear lube widely available at most auto parts stores and at a more reasonable price .

I've got trans, shaft, final drive oil due on the airheads and trans, final drive on the Guzzi, no shaft lube on this bike .

[mrclubike]

It is my understanding that we should use GL-5
The brass they speak of is the synchronizers 
We do not have synchronizers and  no need to worry about the brass cage on the front bearing 
GL-4 is for is for transmissions with synchronizers

[Justin B.]

Bob - The Supertech I wanted was not stocked at the local stores but ordered it at walmart.com for $11.37/qt.  I use 75w140 and find that the transmission seems to shift a lot nicer, especially during hot weatherl.

[Justin B.]

mrclub - This is a GL5 lube but I try to "stock" something that will work in pretty much whatever I have.

[Barry]

Concerns about GL5 oil and any brass in our gearbox is a non issue. It's 25 years since GL5 oil contained unbuffered sulphur that was actively corrosive to yellow metals. Brass Synchro's are still at risk but that is because of a different physical rather than chemical mechanism where the antiwear additive layer is so strong that it peels off a microscopic layer of brass.  In those cases GL4 is appropriate which contains the same additives but only half as much.

The really odd thing about our gearbox and final drive is that there is no logical reason why it should have needed GL5 in the first place because GL5 is specified for hypoid gears and we don't have any. It's what everyone uses though and I'm not arguing against that.

The last synthetic I put in mine was clear as water which felt strange.  I'm curious to see what colour it is when it comes out. Apparently  certain types of base oil are naturally clear and the familiar oil colour is then usually added as a dye.

[Justin B.]

Barry - I drained out Mobil 1 lube that had been in there for 4-5 years and it looked almost new!  The lube out of the final was black but that might be from the migration from the driveshaft.  I'm about due for that plastic washer to be replaced...

[georgesgiralt]

Barry,
BMW specified hypoid lube because these oils have the property of maintaining a film even  under extreme pressures.
And it is advisable to have such properties in our final drives to protect the teeth of the pinions. Incidentally, this is also good for the input shaft torsion device in the gearbox and make no ill effect on the pinion teeth either. So GL5 is a long term insurance against wear.
Just my 2c....

[Barry]

And it is advisable to have such properties in our final drives to protect the teeth of the pinions. Incidentally, this is also good for the input shaft torsion device in the gearbox and make no ill effect on the pinion teeth either. So GL5 is a long term insurance against wear.

I can buy the torsion device as a high stress point of sliding contact but our final drive is a spiral bevel which does not have the sliding contact of a hypoid gear. It's also a good bit more efficient which is a good thing. Compared to a car or truck, our gearbox and final drive  are so utterly spoilt with quality of oil and frequency of oil change that they should last for ever. The final drive does if not perhaps the gearbox.

[Barry]

Barry - I drained out Mobil 1 lube that had been in there for 4-5 years and it looked almost new!  The lube out of the final was black but that might be from the migration from the driveshaft.  I'm about due for that plastic washer to be replaced...

Doing low miles I got fed up with annual draining of pristine looking oil so that's my current plan to leave the synthetic oil in for a few years and perhaps just do a visual inspection for level and condition at each service. Spotting water contamination is probably the only thing to worry about. My drive shaft oil also comes out a bit cloudy so I might change that.

[Lordcargo]

This was a timely discussion since I'm due to change out my fluids.

[Adrian]

A very wise man - in the ways of Airheads - once said to me - about oil...
Always use the oil recommended by the manufacturer or at least it's modern day equivalent.
His reasoning - and it makes sense to me - is that manufacturers spend a lot of time and money researching how best to maintain their bikes.
I have found that this has worked well in my 1984 R65 - I know this as I recently had the motor & gearbox & and drive et al professionally serviced for the first time. Only bearings and seals were needed. All major components were still in good condition.
So there it is - my 2 bobs worth. The only change for me now - as I have had the motor converted to an 860 - will be to use synthetic in the motor - once it's run in on mineral oil - as recommended by my mechanic  8-)