CBS data and engine oil change

[aussiem3]

I have done 35k km in five years of ownership. I change my oil and filter on a yearly basis without waiting for the warning on the car. When I perform this irregular oil changes I don't reset the onboard computer, and let it countdown on its own. Theoretically, I've had one oil change reset, and counting down to my second.

Recently I purchased the Bavarian Technic software and cable. Upon accessing the CBS data through the OBD II port, it was shown 5 oil changes and counting down to the fifth with 21k km to go. Which means the computer has automatically reset following my recent oil change.

I performed by recent oil/filter change in December with no reset. But it appears though the onboard computer is factoring in the quality of the oil circulated through the system and automatically adjusting the DME where the oil change data is kept.

In fact when I look back, I have done four oil changes plus one at 2k km following the break-in period. So the count it was showing is correct. This is really puzzling.

If that's the case I should have got a warning after the third oil change to change the spark plugs, if you go by the service booklet.

Can anyone shed some light on this please?

[gatorfast]

As far as I know the onboard computer does not measure the quality of the oil at all, it simply calculates the next change based on variables such as driving style, miles driven, etc. Therefore, doing a mid-cycle change (which most people on this board do) will not increase the service interval. When I do a mid-cycle oil change, the maintenance countdown is always exactly where it left off.

Additionally, the CBS data will not display a spark plug change. It actually specifically says this in the supplemental manual:

"Spark Plug Service (not shown in CBS): Replace at 37,000 miles."

[aussiem3]

Thank you. I just cannot understand how oil count went up to 5 when I have reset the computer only once.

The maintenance summary page in the service booklet says spark plug change every 3rd oil change ... no mention about 37k miles or 59k km. That's strange as to how there can be different service requirements for the S65 engine.

In fact when you really think about it S65 will do around the above number of miles/km when the computer-based 3rd engine oil change is due. So you're right in one way.

But I still can't get my head around the counter reading five. I read somewhere on TIS that the fuel consumption is factored in for the oil quality and change data. I will look for that piece of information and will post.