15w40 HDEO in a hexhead GS

[dmsantam]

Hello all, my first post, and I have acquired a 2005 model r1200GS with 78,500km on the clock. I am very experienced working on motorcycles, but new to hexheads. Lots of work done on airheads, and Japanese bikes.

 

I am steadily working through a major service and have a query about oil viscosity. I live in Sydney, Australia where the temperature varies between -2C and 43C throughout the year. I see that the owners manual recommends 20w50, and I would happily purchase some conventional 20w50 and use that. However... I also see that 15w40 is "permissable", and I happen to have an excess of 15w40 HDEO that I use in other motorcycles and my (non-DPF) diesel engines. The oil is also API SL rated for gasoline engines. 

 

Is there any good reason why I should buy the 20w50 rather than just use the 15w40 I have? Will the thinner oil at operating temperature cause any issues?

 

cheers. 

[KetoSoi]

15w40 HDEO is pretty much all I have ever used in my '09 RT. Never a problem in cold or hot Northern California weather. Did a UOA at 12,000 miles (6000 on the oil), ridiculous how much life was left in the oil.

 

K

 

[dirtrider]

12 hours ago, dmsantam said:

Hello all, my first post, and I have acquired a 2005 model r1200GS with 78,500km on the clock. I am very experienced working on motorcycles, but new to hexheads. Lots of work done on airheads, and Japanese bikes.

 

I am steadily working through a major service and have a query about oil viscosity. I live in Sydney, Australia where the temperature varies between -2C and 43C throughout the year. I see that the owners manual recommends 20w50, and I would happily purchase some conventional 20w50 and use that. However... I also see that 15w40 is "permissable", and I happen to have an excess of 15w40 HDEO that I use in other motorcycles and my (non-DPF) diesel engines. The oil is also API SL rated for gasoline engines. 

 

Is there any good reason why I should buy the 20w50 rather than just use the 15w40 I have? Will the thinner oil at operating temperature cause any issues?

 

cheers. 

Morning dmsantam

 

That  15w40 shouldn't harm the engine itself but the 2005 hexheads had some issues with seeping rear balance shaft seals (this was changed on later 1200 hexheads). Look at the front of the catalytic converter & rear of engine for signs oil seepage. If you see any signs of oil seepage then personally I would use a  20w50 oil. 

 

 

[lkraus]

If I were just trying to use up some 15w-40, I'd be OK with it. If I had another vehicle that could use it, I'd save it and get some 20w-50 for the bike.  The 15w-40 would probably be just fine, but at the very high temperatures you expect, I'd feel better with 20w-50 in the crankcase. 43º seems like a long way above 30º.

 

My '06 RT owners manual has these recommendations:

 

I've had the leakage around the balance shaft seal that DR mentions, but it started when I began using a synthetic oil(Amsoil 20w-50).  A 3-4 cm puddle would develop under the bike if it was parked for a couple days. The leak stopped when I switched back to a conventional oil.

[dmsantam]

8 hours ago, lkraus said:

If I were just trying to use up some 15w-40, I'd be OK with it. If I had another vehicle that could use it, I'd save it and get some 20w-50 for the bike.  The 15w-40 would probably be just fine, but at the very high temperatures you expect, I'd feel better with 20w-50 in the crankcase. 43º seems like a long way above 30º.

 

My '06 RT owners manual has these recommendations:

 

I've had the leakage around the balance shaft seal that DR mentions, but it started when I began using a synthetic oil(Amsoil 20w-50).  A 3-4 cm puddle would develop under the bike if it was parked for a couple days. The leak stopped when I switched back to a conventional oil.

Interesting, the GS manual i read online (i didn't get one with my bike) said 15w40 for "anything above 0C", but didn't mention an upper temperature.