quadrun
The oil service system on the M5 really does go for 650 litres per green light, or 3250 litres when reset to full "health". Other models probably have different settings because they have different engines with different power outputs and different sized sumps. Mine went 18,500 km, or just under 12,000 miles (mostly city) on the last change. The day I rolled it off the lot with 8 km on the clock, it had 3243 litres left to count down.
On some of the E39's you can read out the "litres to go" by sitting in the drivers seat with the doors all closed, the engine off and your seat belt done up, pushing the left side dashboard button (that normally resets the trip odometer) and holding it, then slowly turning the ignition key until the instrument cluster "just" lights up (key does NOT click) and waiting about 5 seconds. The dashboard readout will tell you how many litres to the next service. Mine counts down from 3250. If you change your own oil, and the system has tripped the "service me" light, you can reset the counter from the same menu point - just hit the "odo reset" button twice more.
Jimbo
Long, long ago, in a universe far away, I had an E36 318is, 1992, that was a dream to drive. It ran best on 94 octane fuel (Chevron in BC, Sunoco in Ontario) and with Castrol Syntec 5w-50 in the sump. It was a great car.
Cheers
JJ