15k miles! I think BMW is having too much trust in oil capacity!
I agree with donYan. I don't let any garage touch my cars after the warenty is over. It's 25 bellow zero outside and the car sit there for one hour. The regular garage will take the car inside shut down the engine, do the oil change in 12 minutes. How can you change oil correctly in 12 minutes with a iced engine and cold oil?
When I trained at VW interamericana,
(let's go back to 1965!) they said the oil was for:
a)- lubricating the parts
(the oil is "carrying" the crank, for instance) so they don't touch one another.
b)- sealing the parts
(rings, seals...etc) for no preasure leaks.
c)- cooling the engine insides
(valves cool trhough their guides & oil flow evacuates that heat to the sump, for instance)d)- cleaning the engine insides
(has detergent) & keeping the wear solids in suspension...that's where changing the oil when HOT is important! All that garbage is eliminated.
The air cooled VW engine had no filter; the cause was that the oil molecule gets destroyed by quick
(or abrupt) temperature changes, like the ones common in aircooled engines. So, the oil was changed every 2,500 Km. With two and a half liters of sump capacity, oil change was
(and still is) cheap. The oil used was Monograde, because it is more robust to temperature changes
(most of the time the VW engine works at high temp ranges).
We say "aircooled" when more than 70% of VW engine parts are oil cooled. Take that oil cooler out, and the engine lasts maybe a week! Or 100 Km on the road...one hour!
My 1963 VW bus never has had the engine case open...now, 8 speedometer turns old...
(in miles! not Km) and works day to day, road or city: uses litle gas, and I am not in a hurry with the lanscapes in this country. Top speed is 90 Ml/h, and goes up to México city
(2,500 meters altitude) at 60 Ml/h loaded...No, not a Porsche at all!
P.D.- MY bus engine has an oil filter: ads half a liter more of lubricant/cooler oil...
