Condition Based Service

[jeffgingras]

Has anyone seen the oil change mileage in their service interval display decrease dramatically in a short period of time?

My car had been showing an oil change due at 16,000 miles until very recently. It now indicates that the oil service will be due at about 6,000 miles.

The only thing I can think of that might have caused this change was a stretch of bitter cold temperatures here a few weeks back. But the car is garaged at home and quite often at work as well. In any event, I can't imagine a week of outside temps in the 0 deg. F range would require an oil change 10,000 miles sooner.

Other than the weather, there have been no changes to my usual daily number of trips, trip lengths, or driving style.

I'm not really concerned that this is a problem. The maintenance is free and I'll take the car to the dealer when it says it is ready. Just curious if anyone else has had a similar occurence in their car.

[Tom K.]

The mileage indicator is a countdown, so if it reads 6,000, that means that the change is due after you've traveled 6,000 more miles, not at an odo reading of 6,000. It does seem that a leap from 16,000 to 6,000 is a bit extreme - although mine has been reading 13,000 for the past 3,000 miles. Earlier models have a slightly different system (readouts rounded to the nearest 25 miles) which seems to be much more linear.

Tom

[richsnuc]

Maybe your oil heats above a target temperature during your normal drive when it's >40F out, but not when it's 0F. I think a large part of the computer logic in deciding when you will need to change your oil is that your engine gets hot enough to drive moisture out of the oil and thus reduce acids and corrosion that may form.

[jeffgingras]

Tom - I realize the service interval display is a countdown. A month ago, with 3000 miles on the odometer, the SID was showing 13,000 miles remaining to the next oil service. Now, with 4200 miles on the clock, the SID shows 1900 miles remaining.

richsnuc - Interesting theory. Most of my trips are 10 miles or less, so in extremely cold weather any water content likely will not vaporize fully. We see a similar effect in reciprocating aircraft engines when they are flown infrequently. Operators think they are helping by starting the engine every few days and letting it idle for several minutes, but not actually flying the aircraft. Rather, the oil becomes very acidic and engine wear is accelerated.

Although it is somewhat disconcerting that my typical driving conditions seem to be hard on engine oil, I am quite relieved that it seems the OCM will reduce the oil change interval substantially if warranted.

[imdanomite]

the condition based oil sensor is based (i believe) on the resistance the oil has electrically. so for you to drive less than 10 miles frequently, then yes...it would make sense. moisture could definately affect the oil change interval.

[cagekicker]

maybe it's your elevation in colorado.