Extra oil change - can you explain it!?

[attila]

Here is the story: I track the car relatively often (4 track days in May only one in June but 4 coming up in July)
So I like to change the engine oil more often than BMW recommends. After the 1,200 mile service I changed it at 4,200 miles and now at 8,000 miles I went in for another oil change. And here is the thing, the SA was telling me that based upon the "key reading" my car needs an oil change (just after 4000miles), so they did it free of charge?? I am not complaining but somehow worried that the oil could have been deteriorated so much that the car needed a change?!!
What is the car actually measuring in the oil? How is it determined by the ECU that the car needs an oil change? By the way no service light came on, nothing was indicating that something maybe not right.
Thanks

[///M Rakete]

Originally Posted by attila

Here is the story: I track the car relatively often (4 track days in May only one in June but 4 coming up in July)
So I like to change the engine oil more often than BMW recommends. After the 1,200 mile service I changed it at 4,200 miles and now at 8,000 miles I went in for another oil change. And here is the thing, the SA was telling me that based upon the "key reading" my car needs an oil change (just after 4000miles), so they did it free of charge?? I am not complaining but somehow worried that the oil could have been deteriorated so much that the car needed a change?!!
What is the car actually measuring in the oil? How is it determined by the ECU that the car needs an oil change? By the way no service light came on, nothing was indicating that something maybe not right.
Thanks

CBS, or Condition Based Service, determines when your car needs use-driven service like oil changes. My understanding is that CBS factors in things like engine time, engine speeds, and fuel consumed, likely as a bias off of a normal 15k mile cycle. So "heavy" use could drive down the cycle but remember that CBS doesn't know about your 4,200 mile change (you did it yourself or the dealer didn't reset CBS as you would have paid for the early service), it is comparing 8,000 miles with the last known service reset of 1,200 miles. It thinks 6,800 miles have gone by. The car doesn't measure anything in the oil.

[JCtx]

Originally Posted by ///M Rakete

remember that CBS doesn't know about your 4,200 mile change (you did it yourself or the dealer didn't reset CBS as you would have paid for the early service)

That's correct, but I was wondering if we reset the CBS ourselves after a DIY oil change if dealer knows we did . They don't do it because the next time the system triggers a tranny and oil differential fluid change along with engine oil. Hmmmmm. They also should be done every 2 years regardless of miles (same as engine oil once a year), but BMW doesn't want to do that.

I just changed my oil with 4,500 miles on the clock because it's been a year since the 1,200-mile service, and was seriously thinking about resetting the CBS (I did reset it with the brake fluid change I did myself), so I could maybe have another tranny and diff oil changes before warranty runs out, but I'll do that myself too. If my car doesn't have a problem (knocking on wood), it probably won't see a dealer again under my ownership .

[attila]

Originally Posted by ///M Rakete

CBS, or Condition Based Service, determines when your car needs use-driven service like oil changes. My understanding is that CBS factors in things like engine time, engine speeds, and fuel consumed, likely as a bias off of a normal 15k mile cycle. So "heavy" use could drive down the cycle but remember that CBS doesn't know about your 4,200 mile change (you did it yourself or the dealer didn't reset CBS as you would have paid for the early service), it is comparing 8,000 miles with the last known service reset of 1,200 miles. It thinks 6,800 miles have gone by. The car doesn't measure anything in the oil.

I see, so that means in 6,800 miles plus about 14 track days I had enough use that I needed a new oild change. In other words it is really a good idea to change your oil way more frequently than the OEM service intervals if you track the car. I drive conservatively on the street with OK (20mpg avg.) milage, so I asume the continous high revs on the track contributed big time to this.

[IND-Distribution]

Even as early as the E30, BMW has used a condition based service reccomendation. The reccomended oil change and service intervals are based on "normal" driving, but the car's computer system will adjust to harder driving and reccomend more frequent maintenance intervals based. I think it's a very neat feature!

[corrupt23jj]

Originally Posted by attila

By the way no service light came on, nothing was indicating that something maybe not right.

If no light or notice indicates that an oil change is needed outside of the normal intervals, then the only way one would know is if their SA reads the key or happens to stop by a dealer, right?

[///M Rakete]

Originally Posted by attila

I see, so that means in 6,800 miles plus about 14 track days I had enough use that I needed a new oild change. In other words it is really a good idea to change your oil way more frequently than the OEM service intervals if you track the car. I drive conservatively on the street with OK (20mpg avg.) milage, so I asume the continous high revs on the track contributed big time to this.

I would say that is a fair assessment. A track day might be worth 500 miles of average driving. Let's take your case, 14 track days, say that's equivalent to 7,000 miles plus the 6,800 makes 13,800 miles. Close enough to a nominal 15k. I'm not going to say that the 1 track day to 500 miles ratio always applies but it isn't unreasonable in my book.

[attila]

Originally Posted by ///M Rakete

I would say that is a fair assessment. A track day might be worth 500 miles of average driving. Let's take your case, 14 track days, say that's equivalent to 7,000 miles plus the 6,800 makes 13,800 miles. Close enough to a nominal 15k. I'm not going to say that the 1 track day to 500 miles ratio always applies but it isn't unreasonable in my book.

Interesting thought and you most likely are right with the 1 track day 500miles conversion. The question is should we apply that not just for the oil change but for other maintenance interval as well.
During my track days I am on the track about 80-100 miles so there is x5 factor for wear and tear compared to normal driving.

[EJ_92606]

Originally Posted by elp_jc

That's correct, but I was wondering if we reset the CBS ourselves after a DIY oil change if dealer knows we did . They don't do it because the next time the system triggers a tranny and oil differential fluid change along with engine oil. Hmmmmm. They also should be done every 2 years regardless of miles (same as engine oil once a year), but BMW doesn't want to do that.

I just changed my oil with 4,500 miles on the clock because it's been a year since the 1,200-mile service, and was seriously thinking about resetting the CBS (I did reset it with the brake fluid change I did myself), so I could maybe have another tranny and diff oil changes before warranty runs out, but I'll do that myself too. If my car doesn't have a problem (knocking on wood), it probably won't see a dealer again under my ownership .

The dealer will do an annual oil change as part of the included maint plan regardless of the CBS indicator. The CBS indicator for oil changes is based on fuel consumed, so hard driving and track days will shorten the oil change interval.

[EJ_92606]

What are people seeing on average in regards to the CBS indicator for oil changes...that is people that don't track their cars? On my 335 its about 14,000 miles..

[JCtx]

Originally Posted by EJ_92606

The dealer will do an annual oil change as part of the included maint plan regardless of the CBS indicator.

I know . Rather pay $200 or so a year in maintenance than letting only dealer in town treat my car like a Geo. Plus I enjoy working on my cars, especially the M3. Prefer to leave the doors open in case I really need them, but my goal is to never have to go back. Hope my car cooperates .

[Splinter4784]

SCREW THE CBS COMPUTER INDICATER

on Everything

15000 mile oil changes is for chumps

Change your oil every 5000 miles

Brake Fluid every 5000 miles

Differential every 7500 miles

Transmission every 10000 miles

and all the other fluids at 10 to 15K miles

Fluid Changes ARE VERY IMPORTANT


And for those that ASk for Proof or Why you should do this


Smash your head against a Brick

[quality_sound]

I don't think asking for proof is an invalid question. If you send you fluids to Blackstone and they come back with an analysis that says the contaminant levels are low enough to use the factory recommended intervals what is there to gain by changing it more often? I'm sure M did quite a bit of research and testing before setting the standard recommended and CBS intervals.

I'm genuinely curious about your response. I understand wanting the car to be in tip top shape but I think your numbers are seriously getting into the diminishing return area.

[tudernos]

Is there and indicator for all these fluid changes such as differential, brake/clutch, and transmission? What's the recommended interval to change these fluids if one is anal and would like to change it not based on the indicator? Thanks!

oil change
differential
brake/clutch
transmission