oil consumption

[andyff013]

Hello everyone, as a relative newcomer to BMW`S and this site, does anyone know what an acceptable rate of oil consumption is? My bike is a 1991 R100GS with 26000 miles on the clock, which I believe is correct.At the moment I use the bike for commuting to work on and in the last 600 miles I have put 750ml of oil in it, which seems a lot.If anybody has any ideas on this then I would appreciate any advice.Thanks!

 

[thornley]

Very high oil loss. Does the bike smoke heavily? Any obvious leaks? I've always used max 200ml per 1000 miles on the R100 engines, hardly noticeable between 2000 mile oil changes. Allowing for this use you're losing 550 ml per 600 miles above expected.

Oil level must be checked cold and should remain between upper and lower lines min/max when checked with the dip stick unscrewed. Check usual leak sites, push rod tube grommets, sump gasket, rocker covers etc plugs should be oiled up if burning oil through the bores at this rate.

 

[andyff013]

Thanks for your reply Thornley,it does seem to be a high usage,there does`nt seem to be any leaks and i`ve had the engine compression tested and both cylinders gave an equal reading of 9.6bar,which I believe is acceptable.On inspection both of the plugs are darker than normal but I would`nt say that they were particularly oily.In the bikes first 13 years it only did 15000miles,I was wondering wether dry valve stem seals could produce this problem which is getting worse the more miles I do.Thanks again.

 

[cookie]

could be valve guides, but 26k doesn't seem many miles even though they seem prone to wear.

i overhauled mine with new guides & rings & it still burns a bit, maybe the same amount as thornley's bike.

what oil is in it? not some poncey 0w-40 stuff that will slip past the rings & down the guides is it?

try decent 20w-50, changed regularly at 2/3k. they seem to like that best IMO

 

[MATKAT]

800-1000

well I reckon on 800-1000 miles a pint on airheads using good old Morris's oils............... nothing does any better on those very loose tolerance super flat twins.......no super duper oils needed.they are designed to run on s**t

 

[andyff013]

Thanks chaps,for your advice,I use a Millers oils 20/50 in it and change at 3000miles. On my way to work yesterday it ran for the last 20miles intermittently on one cylinder,on inspecting the plugs the one which was running intermittently was heavily fouled with a black substance which can only be oil residue.I went up to see Mick Barr in leicester and it will be going in to him for inspection and twin plugging while the heads are off. Once again thanks for your advice and happy biking!