Need to know oil grade for my BMW K1100 RT

only use 5 grade fork oil in the forks not 10 grade or they will be very stiff you need 13.5fl ozs + or - 10% in each leg,,,,

there should be a radio book with the bike and its in the book

probably find that the dog clutch on the end of the starter has given up the ghost,failing that,bmws are critical on the grade of oil used and if you have used a mineral rather than synthetic oil the dog clutch will be gummed up with deposits,sometimes a hot engine flush and new oil(synthetic)will fix it,hope this helps