Transmission Oil

[k547]

2003 K1200RS Transmission Oil

2003 K1200RS

This is the BMW GL-5 oil, part #07510039646 that is "currently unavailable due to supply chain difficulties in supplying it to our dealers". Some dealers still have this in stock but are not receiving more of it at this time. It was implied that this was a temporary situation.



This is what the three 3 BMW dealers I checked with are currently shipping out for orders of part #07510039646



As the last item in changing all the fluids except for the brake fluid which was 12 months old from a San Jose BMW service event in my "new to me" bike I drained the transmission oil and noted the heavy, clinging odor associated with typical 80W-90 hypoid gear oil from the auto parts store (automotive rear differential). Nothing wrong with that as long as it meets GL-5 spec.
I refilled the transmission with the specified BMW branded oil shown above purchased from an ex BMW owner that had some unopened quarts on hand. This oil has none of the "hypoid" smell (it's practically odorless) and appears almost golden in color. It's defiantly different stuff from the usual hypoid gear oil.

I have about 175 miles on the new oil now and I liked the way the bike shifted better with the hypoid gear oil in it before I replaced it with the BMW stuff. The shift lever now (subjectively) feels "stiffer" and harsher, more of a notchy or crunchy sensation changing gears.
I'm planning on draining the BMW oil and replacing it with the Castrol GL-5.

Has anyone else experienced this? Comments/recommendations?

 

[52184]

I have used that Castrol gear lube for a long time in my airheads, oilheads, and brick-k bikes. It’s GL-5 rated, correct viscosity, and since the three series of bikes I mentioned earlier are all running dry clutches no effects at all on clutch operation. And, it’s available anywhere there is a FLAPS.
Go for it, IMHO.

Best,
DeVern

 

[k547]

I drained the BMW branded oil and re-filled with Schaeffer's synthetic gear oil.
My impression is that it is perhaps a slightly marginal improvement over the BMW oil but overall very similar. Shifting feel was still quite harsh and abrupt.
Certainly not as good as whatever it was that I had originally drained out.
Next I have two non synthetics - Castrol and Liqui Moly to try out.
I'm certain that whatever I had originally drained out was not a synthetic from the strong, easily recognizable, odor of standard automotive differential hypoid gear oil.

 

[k547]

I could see no need to prolong the punishment so after a quick 100 miles on curvy, non highway roads (lots of shifting) I drained the Schaeffer's and refilled with Liqui Moly non synthetic gear oil.
The difference was immediately apparent the first time I started the bike and put it into first gear sitting at idle in my garage.
No more "crunchy" stiff feel, it slid into first "effortlessly".
Riding it, the shifting was vastly improved over the two previous synthetic oils and to some degree better than whatever I had drained out originally when I started all this.

Smooth, quiet, silky feeling, hot knife thru butter, blah, blah, blah, yada, yada, yada.

I then drained the fresh synthetic oil out of my rear end gear set and re-filled it with the remainder of the Liqui Moly oil.
I might not even get around to trying the Castrol I like this stuff so much.

Please do not respond as though I'm saying non synthetic is better than synthetic or that I'm saying that Liqui Moly is better than BMW or Schaffer's.

I AM NOT SAYING THIS.
I am not implying anything or recommending anything to anyone else or making any statement regarding oil usage.

All I am doing is reporting how one out of the approximately 38,000 BMW K1200RS motorcycles that were manufactured responded to three different brands/types of transmission oil during my use of it under whatever conditions that I operated it under. I can already imagine waking up tonight with my garage surrounded by angry villagers brandishing torches and pitchforks....

 

[20774]

Interesting experiments! I notice that the oil you seem to like more is the one that is nearly a straight weight oil - 85w90. The others have a wider range in the viscosity limits. Doubt that has an impact, but there is at least a little difference there.

 

[k547]

@ 20774

I tried to stay close to the BMW recommended 80-90W.
I have a 22 year old German car and a 4 year old Japanese car, both with 4 cylinder engines and manual transmissions and I use synthetic gear oil in the transmissions of both of them.
They shift better with the synthetic. My K1200RS seems to be the opposite.
I've owned a lot of motorcycles, European, Japanese and American, dating back to the mid 1970s and I don't recall any of them exhibiting such a big difference in shifting action/feel from using different oil brands/type in either the transmission or the shared engine/transmission.

 

[k547]

@ 20774

Despite being very close in viscosity ratings the Liqui Moly is a lot thicker and more viscous than either the 80W-90 BMW or the 75W-90 Schaeffer's.
It really clings to the side of the glass measuring beaker I used and it took over twice as long for the same measured amount as the other 2 oils did to flow thru the hanging funnel and tubing device I made up to re-fill rear end and transmission fluid.
I could tell because I was listening to the same podcast as before and it ran twice and then some while I was re-filling. The other oils only took slightly less than one play of the podcast.

Maybe the thicker viscosity is what the transmission is responding to? Amazing difference in shifting "feel/quality".
Heck, if it likes "thick" viscosity that much I could pump the transmission full of grease.......

 

[paul_f]

2003 K1200RS


View attachment 93106

This is what the three 3 BMW dealers I checked with are currently shipping out for orders of part #07510039646

View attachment 93107



I have about 175 miles on the new oil now and I liked the way the bike shifted better with the hypoid gear oil in it before I replaced it with the BMW stuff. The shift lever now (subjectively) feels "stiffer" and harsher, more of a notchy or crunchy sensation changing gears.
I'm planning on draining the BMW oil and replacing it with the Castrol GL-5.

Has anyone else experienced this? Comments/recommendations?

I’ve using this for two riding seasons in my ‘98 Oilhead. The bike definitely shifts more easily. A BMW shop that before COVID used give winter workshops always recommended Castro; wish I had started using it years ago.