Sorry about recent post ,I think I,m in the right catagory now.
same old question , but I need to know the answer . You buy a bike then go on e bay and buy some oil , simple !.Not quite , you next find a forum on the web full of proper information . Too late its already in the engine ,did I do right?
fully synthetic 10 / 40 engine oil , yes or no?

you may want to change it sooner than expected, especially before the weather warms up.
get hold of an oil viscosity chart and run comparisons for operating temps in your region.
A 10/40 will keep you going during low temp months ie; about 5 degrees or less, in Australia we run a 20/40 minimum,
for up to 30 degrees, but a 20/50 is much preferred, will run up to 40 degrees.
The manual indicates a good quality HD oil suitable for 4 stroke spark ignition.
at the moment at least you have something in there to lubricate, good luck with it.
Oh and also check the quantity you are using, should be about 3.75 lt ( or 6.6 Imp pint , 6.9 US qrt)
you don't want to be swimming in the stuff.

Thanks Grover K
Reason I put 10/40 in it thats what it had all its life according to the service history from new. I actually didnt expect that
answer, I was really thinking the synthetic part might be the wrong thing.

I would say that you have chosen a good oil there. I use a 5/40 synthetic with no problem in the south of France. As long as it is synthetic the oil will hold its viscosity at very high temperatures. A mineral 20/50 would soon destroy itself at over 140C (oil temperature) and become much thinner than the synthetic anyway.
If you read the owners handbook a 10/40 is good for ambient temperatures of -20 to +20c, but you need to look further down the table as a synthetic is classed as a special oil and the handbook says a 10/40 special oil is good for -20 to infinity.

Made my day ,cheers!

On the forum page type "engine oil" into the search window, there have been many posts on oils for the K and just as many comments.

If you drop into your local BMW and ask for some of there finest oil for me old K.... They will smile and give you 10w 40 Castrol fully synthetic. I use the same one as they sell but get it from Halfords at Trade prices!

My BMW dealer also told me to get the gearbox oil from Halfords which is the right spec and the same gearbox oil go's into the Final Drive....

If your doing the fluids is well worth doing them all....

When I got my K the front end was horrendous.... All it needed was to have the fork oil drained and fresh put in.... I can't remember what I used but it was 10W for the LT

Rover 75 diesel, Peugeot 405 Turbo diesel, K100LT, they all get the 10W40. Frequent oil changes, do them at home. In extremely hot weather it seems the 10W40 is fine as long as it is fully synthetic.

We dont get 40C in Ireland but have often experienced it in France with the car under full load. Temperature gauge can rise quickly......if the bike doesnt have one I would definitely fit one.

I would certainly consider an oil/filter change for a sustained trip in 40C weather. Most hot weather trouble arises from coolant or oil levels rather than wrong specification. The oil is the primary coolant and the level must be right.