It would be helpful to consider all the things that impact proper oil change intervals but if you do low miles in typical riding, major grit problems won't be one nor will severe heat (and as practical matter you'd be hard pressed to get a running BMW motor to fry a modern synthetic.)
For the low miles rider the usual issues are combustion acids and/or water accumulation.
The reality of modern oil chemistry, especially for long service synthetics with high base numbers, is that they are capable of handling water and acid loads that are ridiculously extreme by the stds of 20 yrs ago. Significantly damaging the viscosity index of modern synthetics in a BMW bike motor in low miles is pretty near impossible.What is in contact with or submerged in oil will not be damaged in silly long storage intervals.
What is of more concern is what is not in the oil- anything above the wet sump line that can be exposed to residual moisture trapped in foamed oil or to water vapor vented in, especially for machines seeing wide temp changes in humid climates. Still, even that is no reason to get all twitchy and nervous.
Anytime you do an oil change it should be done after the motor is brought to full operating temp for a while and while the oil is hot.
Not much point to changing oil on a cold motor- you won't do anything to clear that headspace above the oil and you surely won't get the max of old oil out.
My "practical. real world" answer for most is you can easily go a couple years IF the bike gets to full temp for a while when used and your miles stay moderate. (Oil analysis by most suggests at least 8K is very reasonable on R motors, for example, and that's by very conservative criteria. Your bike won't instantly destruct even if you go well outside them.)
What do I do for myself? Generally 7-8K or annual change, whichever comes first but if that "annual" is 18 mths for a bike getting low miles I don't worry about it at all. I'd be a lot more worried about brake fluid exposed to air in some of BMWs whizzie systems.
I've seen oil failures aplenty- but not in any recent time. Some of the old multi viscosity dino oils were crap and turned to glue if they got a bit too hot due to additive failures - easy to do in hard used motors.
Abusing lots of turbo motors with high boost in humid conditions has given me plenty of opportunities to examine oil when motors are literally trying shear it to death and to force water into it at the same time - despite that I've never seen any engine damage attributable to water in oil or to shear damage.
What I have seen is stressed motors operating with low viscosity oils that provided inadequate wear contact shave so much metal that they lost compression in starting conditions and got very hard to start. Even then, once started and warmed, they cranked out close to their previous max power. I had one motor so gouged it looked like gremlins had been carvings its guts with chisels but it still made plenty of power. It got rebuilt mostly because it was a real pita to get started.
Its separated water or excess acids that can do the damage in low miles conditions but actually running into real damage is extremely unlikely. Its nowhere near as easy to damage motor metal in the presence of modern oils as some think.
For the low miles rider the usual issues are combustion acids and/or water accumulation.
The reality of modern oil chemistry, especially for long service synthetics with high base numbers, is that they are capable of handling water and acid loads that are ridiculously extreme by the stds of 20 yrs ago. Significantly damaging the viscosity index of modern synthetics in a BMW bike motor in low miles is pretty near impossible.What is in contact with or submerged in oil will not be damaged in silly long storage intervals.
What is of more concern is what is not in the oil- anything above the wet sump line that can be exposed to residual moisture trapped in foamed oil or to water vapor vented in, especially for machines seeing wide temp changes in humid climates. Still, even that is no reason to get all twitchy and nervous.
Anytime you do an oil change it should be done after the motor is brought to full operating temp for a while and while the oil is hot.
Not much point to changing oil on a cold motor- you won't do anything to clear that headspace above the oil and you surely won't get the max of old oil out.
My "practical. real world" answer for most is you can easily go a couple years IF the bike gets to full temp for a while when used and your miles stay moderate. (Oil analysis by most suggests at least 8K is very reasonable on R motors, for example, and that's by very conservative criteria. Your bike won't instantly destruct even if you go well outside them.)
What do I do for myself? Generally 7-8K or annual change, whichever comes first but if that "annual" is 18 mths for a bike getting low miles I don't worry about it at all. I'd be a lot more worried about brake fluid exposed to air in some of BMWs whizzie systems.
I've seen oil failures aplenty- but not in any recent time. Some of the old multi viscosity dino oils were crap and turned to glue if they got a bit too hot due to additive failures - easy to do in hard used motors.
Abusing lots of turbo motors with high boost in humid conditions has given me plenty of opportunities to examine oil when motors are literally trying shear it to death and to force water into it at the same time - despite that I've never seen any engine damage attributable to water in oil or to shear damage.
What I have seen is stressed motors operating with low viscosity oils that provided inadequate wear contact shave so much metal that they lost compression in starting conditions and got very hard to start. Even then, once started and warmed, they cranked out close to their previous max power. I had one motor so gouged it looked like gremlins had been carvings its guts with chisels but it still made plenty of power. It got rebuilt mostly because it was a real pita to get started.
Its separated water or excess acids that can do the damage in low miles conditions but actually running into real damage is extremely unlikely. Its nowhere near as easy to damage motor metal in the presence of modern oils as some think.
I take umbrage at that remark. 
