X35d CBS-Indicated Oil Change at 9000 Miles

[scchang]

I was planning to do a change every 7500, but this may make it unnecessary (changed at 1200 and am overdue for the 8750 change):

Brought our 2010 X35d to dealer for a couple warranty items. Vehicle info indicated oil change due soon (have 9000 miles). SA said that diesels seem to require oil changes every 8-10K miles. Has anyone heard this?

[Penguin]

Yup, mine asked for an oil change at 9300 miles, and now at 14,000 it is showing 4,000 miles to the next oil change.

[scchang]

Originally Posted by Penguin

Yup, mine asked for an oil change at 9300 miles, and now at 14,000 it is showing 4,000 miles to the next oil change.

I assume you're not doing an interim change every 4500!

[Penguin]

Originally Posted by scchang

I assume you're not doing an interim change every 4500!

You have identified my quandary.

I did a first oil change somewhere below 2K, and planned on intermediate changes. But 4,000 seems a bit low, even though diesels typically need more frequent oil changes due to soot and more blowby.

So here I am with 4K to go with eight quarts of oil and a filter in the garage, and wondering if I should change it. If it wasn't for the indicator, I'd probably be changing it every 6K or so.

[FunfDreisig]

There seems to be a wide range of mileage reported for the initial (and subsequent) 35d CBS Oil Service: 9k-13k. I wonder what exactly is being measured to cause this large a variation?

It seems unlikely that the CBS is based on the actual properties of the oil in the crankcase, since several of us have done intermediate oil/filter changes. And we seem to be experiencing the same wide range as folks who are doing it "by BMW's book". So it must be based on stuff like: number/length of 'trips', avg mph, temps, etc.

Funf Dreisig

[Penguin]

Originally Posted by FunfDreisig

There seems to be a wide range of mileage reported for the initial (and subsequent) 35d CBS Oil Service: 9k-13k. I wonder what exactly is being measured to cause this large a variation?

It seems unlikely that the CBS is based on the actual properties of the oil in the crankcase, since several of us have done intermediate oil/filter changes. And we seem to be experiencing the same wide range as folks who are doing it "by BMW's book". So it must be based on stuff like: number/length of 'trips', avg mph, temps, etc.

Funf Dreisig

FWIW, the vast majority of my miles have been highway, rather than city. Normally, I would expect that city driving would be harder on the oil than highway, so I found the rather quick change to be a surprise.

[ard]

My CBS hit at 11k ish. I'd done it myself at 7k.

[AzNMpower32]

BMW used to use the amount of fuel consumed as the maintenance interval between oil changes. Driving that elicits more wear on the engine (short drives, many cold starts, aggressive driving) also consumes more fuel. Don't know if that remains true today.

[Craig]

Originally Posted by AzNMpower32

BMW used to use the amount of fuel consumed as the maintenance interval between oil changes. Driving that elicits more wear on the engine (short drives, many cold starts, aggressive driving) also consumes more fuel. Don't know if that remains true today.

[Penguin]

Originally Posted by AzNMpower32

BMW used to use the amount of fuel consumed as the maintenance interval between oil changes. Driving that elicits more wear on the engine (short drives, many cold starts, aggressive driving) also consumes more fuel. Don't know if that remains true today.

If they use the same philosophy, then they must have a different constant between gasoline and diesel. I find the diesel mpg falls dramatically on short trips, yet my change indication came in at the short end of the range, with mostly highway travel at 26-28 mpg. about 5,600 miles of the interval were on a trip, with daily highway travel of 500-700 miles, much of it on Interstate with 28 mpg.

I would be surprised if they simply monitored fuels usage, as that is a rather simplistic approach that was used years ago. GM moved to a much more sophisticated algorithm a long time ago:

GM's Oil-Life System Improves Timing of Oil Change

Surely BMW is at least as advanced as a ten-year-old GM system.