Final Drive oil questions

[JayW]

I drained and refilled my final drive last year, and like many others have since learned that the 75W-140 gear oil I used is no longer recommended for Hexhead final drives. I am going to do the job again using 80W-90 gear oil, but I don't see that BMW offers a synthetic version of this. I would prefer to use a BMW lubricant, but would also like it to be synthetic. Given the Hexhead FD durability concerns, I want to give my FD every possible benefit.

 

So does BMW make a synthetic 80W-90 gear oil? Also, what is the current recommended change interval for this fluid?

 

Jay

[flexibleflyer]

I used Mobil 1 75 / 90 synthetic in my final drive.

 

Bob

[Ken H.]

Doesn't have to be BMW brand, the admonishment is to stay away from 75W-140 or similar.

[BMWRich58]

I drained and refilled my final drive last year, and like many others have since learned that the 75W-140 gear oil I used is no longer recommended for Hexhead final drives. I am going to do the job again using 80W-90 gear oil, but I don't see that BMW offers a synthetic version of this. I would prefer to use a BMW lubricant, but would also like it to be synthetic. Given the Hexhead FD durability concerns, I want to give my FD every possible benefit.

 

So does BMW make a synthetic 80W-90 gear oil? Also, what is the current recommended change interval for this fluid?

 

Jay

 

How'z about this

[Anton Largiader]

... have since learned that the 75W-140 gear oil I used is no longer recommended for Hexhead final drives.

 

AFAIK it never was recommended, at least not by BMW. The only spec I ever had was 75W90. Some dealers used 140, and I don't think it's necessarily a problem, but I don't see any reason to use anything other than the recommended 75W90 synth.

[marcopolo]

Let me quote from a February 2005 BMW USA Service Bulletin #33 001 05 (011). It concerned the 1200 GS, and the subject of the bulletin is "Bearing play at the rear wheel drive". The part of that bulletin pertinent to this thread is the following: "When filling the rear drive assembly with oil, pour in the defined quantity (0.25 l for initial fill, or 0.23 l for oil changes) through the bore for the ABS sensor. We highly recommend using BMW Super Synthetic Gear oil. 75W90, P/N 07 51 0 394 082." I presume that's the product in the photo above in BMWRich58's post.

 

BTW, the final drive on my R12RT failed last summer in Wyoming while on a long road trip. It was replaced, under warranty, at BMW of Salt Lake. They used 75W90 synthetic to fill the new drive. A week later, I had the final drive fluid changed at Brown Motor Works in Pomona, California. They too used 75W90 synthetic.

 

That said, both the service DVD, and parts fiche, call for Castrol SAF-XO. However, I understand that the Castrol product is not available at BMW bike dealers in the U.S. Some suggest trying BMW car dealers. My local independent tech uses the Castrol product in my RT's final drive because, as he says, "that's what BMW specifies". It's not cheap stuff. He charged $5 per 100 ml, or $15 for the fluid change (at least he didn't charge me for a litre).

 

Why not use the super synthetic 75W90 that BMW USA recommends?

 

As for change intervals, the only thing I've heard of is the service bulletin which called for the fluid to be changed once at the 600 mile running-in check. Maybe the 2008 RT manual covers this subject now. I plan to change mine every 25,000 miles, or annually (whichever comes first).

[smiller]

My local independent tech uses the Castrol product in my RT's final drive because, as he says, "that's what BMW specifies". It's not cheap stuff. He charged $5 per 100 ml, or $15 for the fluid change (at least he didn't charge me for a litre).

I think that he's mostly trying to protect himself against the final drive failing someday and a customer claiming that it was his fault because he used the wrong oil. If he sticks religiously to BMW's service manual recommendation then he's covered.

 

In the real world though I can't imagine why commonly-available Mobil 1 75W-90 wouldn't be just fine.

[marcopolo]

In the real world though I can't imagine why commonly-available Mobil 1 75W-90 wouldn't be just fine.

 

As long as it's the same spec, I don't see why not either. I presume the stuff BMW USA recommends is equivalent to the Castrol SAF-XO.

[JayW]

Thanks, Rich. I couldn't read the tiny writing on the internet picture of the bottle I found, and the product description did not specify if it was synthetic or not.

 

I used the 75W-140 last year because that was what the dealer recommended. My owner's manual claimed that the FD had a "lifetime fill" so had no weight recommendation. Of course now a changeout is recommended at 600 miles, but I am not aware of any specific recommendation beyond that. I'll probably go with an annual fluid swap, which for me is about 12,000 miles. I'll stick with the BMW brand, though I agree that Mobil 1 gear oil would almost certainly work just fine.

 

Thanks to all who responded.

 

Jay