The engine must have been stopped for a few minutes so that the level settles before it can be checked accurately. If the engine is cold, warm it up to normal operating temperature, then switch off and wait before checking the level. With the machine on its center stand, on level ground, check the oil level as seen in the sight glass set in the right-hand side of the crankcase lower section. The maximum and minimum level marks are indicated by imaginary horizontal lines drawn through the top and bottom of the circle marked on the glass; the oil level should be maintained between these marks; ie somewhere in the circle, at all times. Never run the engine with the level below the circle or above it; both conditions can lead to engine damage.
If topping-up is required, remove the filter plug from the rear end of the engine right-hand outer (crankshaft) cover and add the required amount of oil; it will take approximately 0.6 liter (1.06 Imp pint, 0.63US qt) to fill the crankcase from minimum to maximum. Use only a good quality, heavy-duty oil suitable for 4-stroke spark ignition engines. Refer to the accompanying thermometer chart to decide what viscosity of oil is necessary at the prevailing outside temperatures. BMW recommend that a medium range multigrade, eg 10W30 is preferable to a wide range multigrade, such as 10W50, and that multigrades are preferable to monogrades.
Engine oil viscosity selection chart
Note: In normal use the sight glass will be self-cleaning, but if the machine is used only in cold weather, or infrequently, or for very short journeys only, the glass will become obscured by deposits of emulsified sludge. The only way to avoid this is to take the machine regularly on a journey of sufficient length to warm it up thoroughly; this will evaporate the moisture from the oil and should clean the glass.
If this not possible, the engine oil must be changed at more frequent intervals (see additional recommendations) to keep it and the engine clean; note that the starter clutch may slip on early models if the sludge deposits are allowed to build up too much.
Next Section: 3. Check the fuel level
Engine oil level must be maintained between maximum and minimum level lines
Use only good quality engine oil specified type when topping up