[WilliamE92]

I know these engines have some sensor that runs off of witchcraft that can tell how dirty your oil is. However, since I change my own every 4-5k, shouldn't the sensor read that my oil is "clean" again and reset?

I bring this up because apparently my engine thinks that my oil is so dirty that I need to take my car in 5k miles early to get it changed at the dealership, despite changing it twice since my last visit. I don't want to take it in any earlier than I need to, so...

Also, whats the dealership stance on taking your vehicle to an independent shop to get the tranny flushed? Not that they have to know ; )

Thanks.

[OlivaresAnthony]

The sensor doesn't read how "dirty" your oil is. It is just a mileage countdown from the last time it was reset.

[DPritchett]

Agreed -- all that talk about condition based sensors not withstanding, the mileage to the next oil change does not adjust up if you do an intermediate change.

[bimmertt]

Originally Posted by OlivaresAnthony

The sensor doesn't read how "dirty" your oil is. It is just a mileage countdown from the last time it was reset.

you sure about this? I thought it was called condition based service for a reason...

[F32Fleet]

Originally Posted by bimmertt

you sure about this? I thought it was called condition based service for a reason...

The condition of the oil is part of the algorithm but not end all.

[F32Fleet]

Originally Posted by WilliamE92

I know these engines have some sensor that runs off of witchcraft that can tell how dirty your oil is. However, since I change my own every 4-5k, shouldn't the sensor read that my oil is "clean" again and reset?

I bring this up because apparently my engine thinks that my oil is so dirty that I need to take my car in 5k miles early to get it changed at the dealership, despite changing it twice since my last visit. I don't want to take it in any earlier than I need to, so...

Also, whats the dealership stance on taking your vehicle to an independent shop to get the tranny flushed? Not that they have to know ; )

Thanks.

No because total miles driven or time is part of the algorithm. Push out your OCI to 7,500 odometer miles and it'll work better. Remember in order to keep your warranty intact you must at a miniumium have on record your car has been serviced at the appropriate intervals.

[jaguar36]

Originally Posted by OlivaresAnthony

The sensor doesn't read how "dirty" your oil is. It is just a mileage countdown from the last time it was reset.

It's not just a mileage countdown, it takes into account a slew of variables like engine starts, temp, engine speed and such. It doesn't sense anything about the oil directly though.

[ENINTY]

The oil level sensor does evaluate quality of the oil by the electrical properties (capacitance) of the oil to determine when replacement of the oil is necessary. It is part of the algorithm used to determine the oil service life along with cold starts, cold RPMs, fuel consumption, miles driven, etc. The sensor can only determine when the oil is considered used to a point of replacement when it reaches a predetermined value for (“dirty” oil) capacitance. The sensor cannot tell when the oil is changed with new oil in the crankcase because the sensor only sees the capacitance as either within the limits of good oil, or over the limit for dirty oil. The CBS needs to be reset when the oil is changed to let the algorithm start counting all over again.

[jaguar36]

Originally Posted by ENINTY

The oil level sensor does evaluate quality of the oil by the electrical properties (capacitance) of the oil to determine when replacement of the oil is necessary. It is part of the algorithm used to determine the oil service life along with cold starts, cold RPMs, fuel consumption, miles driven, etc. The sensor can only determine when the oil is considered used to a point of replacement when it reaches a predetermined value for (“dirty” oil) capacitance. The sensor cannot tell when the oil is changed with new oil in the crankcase because the sensor only sees the capacitance as either within the limits of good oil, or over the limit for dirty oil. The CBS needs to be reset when the oil is changed to let the algorithm start counting all over again.

Do you have a source for that info? Reason I ask is that it doesn't make any sense.

If it could sense when the oil was "over the limit" then your CBS would all of a sudden go to zero.

In addition the only part listed as an oil sensor, is the oil level sensor, which only measures the level, and not the "capacitance".

Lastly, when an oil analysis is done by someone like Blackstone, they don't measure the "capacitance" of the oil. If this were the magical dirty oil indicator, why wouldn't they measure it?

[F32Fleet]

Originally Posted by jaguar36

Do you have a source for that info? Reason I ask is that it doesn't make any sense.

If it could sense when the oil was "over the limit" then your CBS would all of a sudden go to zero.

In addition the only part listed as an oil sensor, is the oil level sensor, which only measures the level, and not the "capacitance".

Lastly, when an oil analysis is done by someone like Blackstone, they don't measure the "capacitance" of the oil. If this were the magical dirty oil indicator, why wouldn't they measure it?

Eninty is speaking the truth. Capacitance is just part of the algorithm and not an end all. Mileage/time is another.

Blackstone UOA measures wear particles of X-size in PPM (this is a problem in itself), and they have nothing to do with what we're talking about.



(See attached)

[ENINTY]

Originally Posted by Socom

Eninty is speaking the truth. Capacitance is just part of the algorithm and not an end all. Mileage/time is another.

Blackstone UOA measures wear particles of X-size in PPM (this is a problem in itself), and they have nothing to do with what we're talking about.

Capacitance is just part of the algorithm and not an end all.

(See attached)

Thank you kind Sir. I appreciate the support.

[ENINTY]

Originally Posted by jaguar36

Do you have a source for that info? Reason I ask is that it doesn't make any sense.

If it could sense when the oil was "over the limit" then your CBS would all of a sudden go to zero.

In addition the only part listed as an oil sensor, is the oil level sensor, which only measures the level, and not the "capacitance".

Lastly, when an oil analysis is done by someone like Blackstone, they don't measure the "capacitance" of the oil. If this were the magical dirty oil indicator, why wouldn't they measure it?

Get the Bentley repair manual for your E90. It fully explains how the car is built, operated, and repaired. Engineers do many things. Problem solving is their main focus. Through the scientific method, engineers develop a therom, test the therom, and re-test to make sure their therom is correct. The engineers tested oil that was considered "spent" and measured the capacitance of it. They then developed an oil level sensor that measures capacitance of oil so that they can tell when the oil has reached a state where it no longer provides the properties to prevent sludge buildup in the the engine (which is the cause of engine failure) and along with other measured values mentioned previously, triggers a call for an oil change.

[jaguar36]

Originally Posted by ENINTY

Get the Bentley repair manual for your E90. It fully explains how the car is built, operated, and repaired. Engineers do many things. Problem solving is their main focus. Through the scientific method, engineers develop a therom, test the therom, and re-test to make sure their therom is correct. The engineers tested oil that was considered "spent" and measured the capacitance of it. They then developed an oil level sensor that measures capacitance of oil so that they can tell when the oil has reached a state where it no longer provides the properties to prevent sludge buildup in the the engine (which is the cause of engine failure) and along with other measured values mentioned previously, triggers a call for an oil change.

Ahh yes, thank you for the overview of what an engineer does, I was unaware.

Reading up on it some more it seems that the capacitance of the oil is directly related to the amount of small conducting particles in the oil.

So, has anyone figured out how to get a reading from this sensor directly? Would certainly be interesting to see how it changes as the oil ages. Also how come mid-cycle oil changes seem to have no effect on the CBM countdown?

[SeriousE92]

Does anyone have a pdf or directions on how to reset the oil meter/life/CBS tracker?