kabalah70 said:
IMHO, having the oil changed based on miles for the Karma is silly, wasteful, and wrong since it is merely the drive unit for a generator. Military generator sets base oil changes based on a time schedule and hours of operation, i.e. every 500 operating hours, but at least once per year. I think Fisker would save a bunch more money doing it this way and our cars would not be any worse for the change.
For conventional cars, distance traveled is a reasonable approximation of "engine use", which itself is a useful metric to measure oil life.
As has been noted, with a PHEV distance traveled no longer has a very high correlation with engine use. For people who drive in Sport most of the time it will be reasonably close, but with our engine's operation profile "engine use" is not as strongly correlated with oil life anymore. For people who drive in stealth some or most of the time (most of us, I suspect) distance traveled is essentially meaningless.
Our usage of the engine is much closer to the model followed by aviation; the distance a plane flies is not a particularly good approximation for how much the engine is used, as it doesn't account for ground operation, and varies widely by mission (many short flights uses the engine very differently than one long one, even if the distances match) In the aviation world, the two factors that trigger the need to change the oil are calendar time (every x months, for example) or by directly measuring engine use via a Hobbs meter or some other monitor. For light aircraft for hire or rent, for example, the engine oil is generally changed every 50 Hobbs hours.
I suspect that somewhere the car is keeping track of engine operation hours, but this data isn't exposed to us. I don't know if there are "Service Soon" indicators in the car that actually use this data, but I'm skeptical. Fisker's own printed service intervals speak in terms of miles driven.
Brent
