10w-60 in the F800GS ?

[m0ng00se]

Hi Guys,

I have this weird rattling noise coming from my engine, especially when hot. I have actually had this for quite some time.

On my recent trip down Africa, I changed my oil in Kenya to 10w-60 as it was the only oil I could find (in a KTM shop) and I can't recall hearing that same noise for the rest of the trip. The engine sounded much better and "tighter" if you know what I mean.

Once I reached South Africa, I took my bike to a local BMW dealer and just out of interest I asked them about the rattling sound (however it wasn't so bad then since I had that 10w-60 in). They said it could be CAM chain tensioner (which I have replaced before to no avail) or my cam chain could actually be stretched.

Anyway ... they bike and myself are now back in the UK and had it recently serviced and they put in 20w-50 according to the job sheet and now the rattling is much louder again especially when hot.

I came up with this theory, since the 10w-60 was a thicker oil, it doesn't loose so much oil pressure when hot, hence the cam chain tensioner places more tension on the cam chain and the engine sounds better. With the thinner oil, when hot, oil pressure drops and the cam chain become looser, hence the rattling, makes sense ?

I would like to go back to 10w-60, but was just curious if anyone out there would suggest otherwise ?

Also, anyone replaced a cam chain on an F800GS before ? How big of a job is that ?

Thanks.

 

[skywalker]

20/50 is too thick I'm surprised the clutch isn't dragging. There's something
wrong if its rattling its tits off

 

[m0ng00se]

20/50 is too thick I'm surprised the clutch isn't dragging. There's something
wrong if its rattling its tits off

you are right yes, 20w-50 is thicker. I bought Motorex 10w-60 (as recommended for the KTMs) in Kenya and I am going to change back to that this weekend and compare. If it's not as bad, then I think it could be an oil / oil pressure related issue. I think the 10w-60 didn't get too thin at high temperatures.

I have had this problem for a long time, engine had a rebuilt at around 14000 miles, luckily under warranty and I think it has never been the same since (currently on 35000 miles).

I think I just wanted to check if anyone out there would definitely not recommend 10w-60 for long term use, but I am going to do it anyway

 

[v8legend]

I always thought that 10w40 related to the viscosity range. So, whilst 20w50 wouldn't be ok, 10w60, or even 5w45 (if they made such a thing) would be fine. My undertanding is that it relates to how thin it is when cold, compared to how thick it stays when warm.

Having said that, I wouldn't want to move away from the manufacturers spec unless I was in extreme climates.

 

[curiousexplorer]

Hi, mongoose, I switched from semi-synthetic (that my dealer puts in) to fully-synthetic (10W-40) that made it quieter and less viby, more dampening effect? also the oil does not get dirty that fast.

 

[TheJoker]

I should know better than to stick my nose into an oil-thread, but I wanted to say just one thing.
The specifications you should be looking at is the JASO classifications. The viscosity is only part of the specs.

 

[SCVGS]

Been running Motorex 10W60 full synth since 1600 miles (now at 10K) no issues.

the numbers refer to the cold viscosity of the oil (10W) and what viscosity the oil will protect like when hot (60). Because the 800GS motor is a semi dry sump motor clutch drag is not an issue. Clutch slippage is more common when using the higher weight oils.