# Computer calculation of next oil change



## BimmerVSR (Mar 19, 2004)

I did an out-of-pocket oil chg on my new X535d at 2,000 miles. Will this change the interval for my "free" oil change? When I first started driving my new X5, the computer was calling for a chg at 10,000. Now that I am at 4,500 miles, it is saying 7,000 more miles to next chg.

Was the adjustment tied to my changing the oil or simply my driving characteristics?

My Indy shop did not reset any service indicators.

Thoughts?

Thanks!


----------



## F32Fleet (Jul 14, 2010)

The mileage inticated on the CBS is not actual miles, but a compilation of a variety of factors (probably, #days since last reset of CBS, actual miles driven, fuel consumption, oil permissivity (sp?) etc etc). In the end I believe your oil change will lenghten the computer based OCI but by how much who knows.


----------



## dnaer (Jan 13, 2011)

When I do intermediate oil changes on the 335D, it does not change the CBS interval at all in my 28,000 mile experience. My GUESS is that the CBS has adjusted or compensated for your driving style since this is a new vehicle. To my knowledge, the CBS does not have any capability to measure oil quality but only uses how much fuel has been pushed through the injectors to give change intervals(example... after 400 gallons of fuel have gone through the injectors it's time for an oil change whether you have gotten 20 mpg(8,000 miles) or 30 mpg (12,000 miles)


----------



## Flyingman (Sep 13, 2009)

Dnaer,

There was a thread on this and it was verified that indeed there is an oil sensor that is able to measure certain qualities of the oil. Conductivity was one of them, indicating water. Not sure what else it does.


----------



## dnaer (Jan 13, 2011)

Oops, must have missed that one.... sorry. If that is the case, I wonder why my CBS does not change the oil interval after I do my out-of-pocket oil change?


Flyingman said:


> Dnaer,
> 
> There was a thread on this and it was verified that indeed there is an oil sensor that is able to measure certain qualities of the oil. Conductivity was one of them, indicating water. Not sure what else it does.


----------



## Penguin (Aug 31, 2003)

The mileage indicator is a bit flaky, at least on my X5. While on a trip it said I had 1,800 miles to the next oil change when I stopped one night. When I drove it 50 miles the next morning, all of a sudden it said I was overdue for an oil change.

The oil sensor does measure one or two qualities of the oil, but I don't think it actually uses them in the oil change computation. Rather I think the condition sensor is more of a back-up, and if certain limits are exceeded, it asked for an oil change. I speculate that might be what happened to me, i.e., the oil sensor somehow got an errant reading exceeding limits and based on the reading set the "miles to oil change" immediately to zero. The oil condition sensor is part of the oil level sensor assembly, and the morning this happened to me, there was a screwy oil level reading on the i-drive, giving a false indication of very low oil.

P.S. In answer to your question of " Will this change the interval for my "free" oil change?," the evidence I have seen would say no.


----------



## BimmerVSR (Mar 19, 2004)

Thanks for all the feedback. Seems as though my changing the oil has little or no impact on the computer. So, according to BMW, my first oil change would have been around 11-12K miles. 

I did one at 2K and I guess I will do another at 6-7K. Then I will take my freebie and begin alternating free/pay. I plan to keep this one for a while.


----------



## Snipe656 (Oct 22, 2009)

I have noticed as I approach the 12 month period that the mileage estimates drop like a rock.


----------

