[chinoxs203]

i always read that people think the oil change is based on certain amount of miles, but this might prove different. got a flyer in the mail today with some cool tips and this is always a topic on here.

"not based on time interval but on how you drive"

[bulldog_yyc]

ok so the computer calculates it based on a certain set of threshold parameters. Who says those parameters are adequate technically or were they backed into by financial analysis? Ie calculate the longest possible interval, given an everage bmw driver, that we can run the oil for, given that it costs BMW X dollars per oil change and the cost of not changing the oil is Y dollars of waranty work/vehicle repair (ie the concequences of not chaning oil to often).

Since the consequences of not changing your oil often enough occur into the future, typically to the latter end of a car's useful life, when present valued, that amount would be small when compared to the incremental costs in the short term that BMW has to pay to change your oil more frequently, assuming a certain % of problems or engine failures.

In the end, it probably works fine for most average drivers

[Nick@aep]

That surprises me, because mine didnt say anything until 1k miles before the 15k service was required...Seems on par with the documented schedule, at least.... However, this concept is a cool idea if it did, infact, actually work that way.

[ToadHollow]

Originally Posted by turkish335

ok so the computer calculates it based on a certain set of threshold parameters. Who says those parameters are adequate technically or were they backed into by financial analysis? Ie calculate the longest possible interval, given an everage bmw driver, that we can run the oil for, given that it costs BMW X dollars per oil change and the cost of not changing the oil is Y dollars of waranty work/vehicle repair (ie the concequences of not chaning oil to often).

Since the consequences of not changing your oil often enough occur into the future, typically to the latter end of a car's useful life, when present valued, that amount would be small when compared to the incremental costs in the short term that BMW has to pay to change your oil more frequently, assuming a certain % of problems or engine failures.

In the end, it probably works fine for most average drivers

Damn ............ I just had a college flashback. and =

[thisguyhere]

Originally Posted by turkish335

ok so the computer calculates it based on a certain set of threshold parameters. Who says those parameters are adequate technically or were they backed into by financial analysis? Ie calculate the longest possible interval, given an everage bmw driver, that we can run the oil for, given that it costs BMW X dollars per oil change and the cost of not changing the oil is Y dollars of waranty work/vehicle repair (ie the concequences of not chaning oil to often).

Since the consequences of not changing your oil often enough occur into the future, typically to the latter end of a car's useful life, when present valued, that amount would be small when compared to the incremental costs in the short term that BMW has to pay to change your oil more frequently, assuming a certain % of problems or engine failures.

In the end, it probably works fine for most average drivers

say what???

[bulldog_yyc]

LOL - never mind - thats how an engineer who is now in finance thinks

basically, what is cheaper in the long run for BMW?

A) Cost of changing oil frequently but fewer warranty repairs in the future due to poor oil changes
B) Cost of less frequent oil changes but more warranty repairs in the future

Obviously there are other factors involved, this is a simplification. But in general terms, since the warantee repairs occur in the future, when BMW calculates what this cost would be today, it may be that its lower than the cost of doing a series of oil changes in the short term. Also, not all engines will fail due to poor oil (or can be proven to fail due to it), so assign a lower probability to that number and the present value shrinks even more.

I would love to believe that a room full of bmw engineers cranked out the threshold numbers that the ECU uses. Engineers, by nature, over design many things. Once the finance folks get a hold of it, it becomes, lets say more economical or never "flies"

[SoCalTech]

There are several things that the DME looks at to calculate the oil life. Miles driven, how hard those miles are driven, how much fuel is used, freeway vs in town, cold engine vs hot, and also the condition of the oil (using a condition sensor built into the level sensor), and probably other stuff that I'm forgetting right now.

[E90330iS]

so.... changing according to their interval safe or no!?!

[David 12]

If you are running any kind of tune, I would say no.

[nicknaz]

Originally Posted by turkish335

I would love to believe that a room full of bmw engineers cranked out the threshold numbers that the ECU uses. Engineers, by nature, over design many things. Once the finance folks get a hold of it, it becomes, lets say more economical or never "flies"

all of the used oil analysis reports I've seen for E9X show that the engine oil additives are almost all used up at around 10000 miles, and the CBS still had a couple of thousand miles remaining before an oil change was indicated. I'm not well versed on what happens to engine oil at that point, but since the additives are there to do things like keep build up from forming, and prevent engine wear I would personally want to change the oil at 7500 miles before additives run out, and then increase the change intervals based on remaining additive and the wear metals seen in the oil

That said, I'm not a 'BMW engineer' and my car is leased, so whatever. I'm sticking with the OEM recommended service intervals and calling it a day

[Fritzables]

Yes, Nick is pretty close to the mark. I have access to an oil analysis laboratory through work and get mine checked regularly.

Basically, engine oil wears out which is based on environmental conditions, fuel burnt and mode of driving - obviously the oil quality itself has a bearing on the matter as well.

I change mine every 5,000K's which is based on our humidity and the way I drive.
If you have doubt, take your oil to a lab and get an IR analysis done on it to see what components are failing in your oil for the amount of K's you do.

Fritzables.

[davig]

Originally Posted by E90330iS

so.... changing according to their interval safe or no!?!

Not if you plan to keep the car after the warranty expires. All BMW cares about is getting these cars past warranty at the lowest possible cost. The "free maintenance" is essentially a marketing gimmick.

[w00kiec00kie]

dunno, I don't think I drive that harshly, but my car asked me to get an oil change at around 12k miles -.-

[F104]

Originally Posted by SoCalTech

There are several things that the DME looks at to calculate the oil life. Miles driven, how hard those miles are driven, how much fuel is used, freeway vs in town, cold engine vs hot, and also the condition of the oil (using a condition sensor built into the level sensor), and probably other stuff that I'm forgetting right now.

Hate to dissapoint you but according to bmwfans.info all we have on our cars is an oil pressure switch, and level sensor. The technology for quality sensors is not quite there yet. So the only thing the ECU can look at is number of cold starts (against coolant temp) and operating hours which is the general standard for filter elements. Mileage interval is then simply your average indicated speed times allowed hours, maybe corrected for number of cold starts. But surely no more hi tech calculations.

[Blk07335i]

Originally Posted by F104

Hate to dissapoint you but according to bmwfans.info all we have on our cars is an oil pressure switch, and level sensor. The technology for quality sensors is not quite there yet. So the only thing the ECU can look at is number of cold starts (against coolant temp) and operating hours which is the general standard for filter elements. Mileage interval is then simply your average indicated speed times allowed hours, maybe corrected for number of cold starts. But surely no more hi tech calculations.

I agree... maybe mpg as well.

[E90330iS]

interesting

[jpsum]

Originally Posted by turkish335

ok so the computer calculates it based on a certain set of threshold parameters. Who says those parameters are adequate technically or were they backed into by financial analysis? Ie calculate the longest possible interval, given an everage bmw driver, that we can run the oil for, given that it costs BMW X dollars per oil change and the cost of not changing the oil is Y dollars of waranty work/vehicle repair (ie the concequences of not chaning oil to often).

Since the consequences of not changing your oil often enough occur into the future, typically to the latter end of a car's useful life, when present valued, that amount would be small when compared to the incremental costs in the short term that BMW has to pay to change your oil more frequently, assuming a certain % of problems or engine failures.

In the end, it probably works fine for most average drivers

Agreed 100%. That's why I do a mid-year oil change myself. The oil filter is so easy to change out. I highly recommend at least changing out the oil filter if you don't want to do an oil change. Today's oil might be more advanced than years ago, but filter technology hasn't advanced as much.

[SoCalTech]

Originally Posted by F104

Hate to dissapoint you but according to bmwfans.info all we have on our cars is an oil pressure switch, and level sensor. The technology for quality sensors is not quite there yet. So the only thing the ECU can look at is number of cold starts (against coolant temp) and operating hours which is the general standard for filter elements. Mileage interval is then simply your average indicated speed times allowed hours, maybe corrected for number of cold starts. But surely no more hi tech calculations.

I have no way of proving you wrong without distributing copywright info. But trust me, I'm a BMW certified technician. I've taken several classes at the BMW training center, with BMW training materials. I've also seen a code thrown in a car for contaminated oil. These cars do look at the condition of the oil. The oil level sensor also is a condition sensor, and a temperature sensor.

[742]

Originally Posted by SoCalTech

I have no way of proving you wrong without distributing copywright info. But trust me, I'm a BMW certified technician. I've taken several classes at the BMW training center, with BMW training materials. I've also seen a code thrown in a car for contaminated oil. These cars do look at the condition of the oil. The oil level sensor also is a condition sensor, and a temperature sensor.

There are a lot of considerations that define the condition of the oil in the sump. It would be fairly easy to detect water contamination for example. On the other hand it would take a large lab and a lot of time to determine if all of the standards embodied in LL01 were still being met.

So to say that the system monitors the condition of the oil is not the same as saying that the system can determine if the actual oil still meets all of its specs.

[F104]

Originally Posted by SoCalTech

I have no way of proving you wrong without distributing copywright info. But trust me, I'm a BMW certified technician. I've taken several classes at the BMW training center, with BMW training materials. I've also seen a code thrown in a car for contaminated oil. These cars do look at the condition of the oil. The oil level sensor also is a condition sensor, and a temperature sensor.

Thanks, I think I'll have to eat my words. Never imagined we had this, even though it is not a 100% solution. I first tried to unplug the sensor to see how may pins, but with my hands i can't get to it. Did some googling instead and looks like you're right, see below. The 2nd one would back up why BMW would sue dealers using different oils

From (a lot more on BMW's service interval on this page): http://www.bobistheoilguy.com/forums...095774&fpart=1
* The condition of the engine oil is monitored by a sensor in the oil pan. This sensor obtains the requisite information by measuring the electrical properties of the oil, which change as wear progresses and the additives in the oil become depleted.

From a GM forum:
* Oil condition sensors in some BMW and Mercedes products are useful, also. They have their limitations, though, as they can be blind to some contaminates and can, themselves, be contaminated by certain markers or constituents of certain engine oils. Oil condition sensors can only react to the specific oil at that moment and they add complexity, cost and another potential item to fail. One other beauty of the GM oil life monitor is that it is all software and does not add any mechanical complexity, mass, wiring or potential failure mechanism.

[ENINTY]

So this is the 20 millionth thread on this subject. I think I am the only one I've read that has actually followed the oil service schedule on my BMWs. I have a 1989 E30 with 293K miles; 12,000 mile oil change intervals. 120,000 miles was on non-synthetic oil (but with BG additive early on). I switched to Mobil 1 at about 130K miles. The motor is still running fine. I also have a 1997 Z3. Oil changes average also about 12,000 mile intervals. The car has 140K miles. The engine runs perfect. My E90 has 75K miles, motor is strong as the day I bought it. I've averaged about 17,500 miles between changes. I am the original owner of all three cars.

[F104]

Originally Posted by ENINTY

So this is the 20 millionth thread on this subject. I think I am the only one I've read that has actually followed the oil service schedule on my BMWs. I have a 1989 E30 with 293K miles; 12,000 mile oil change intervals. 120,000 miles was on non-synthetic oil (but with BG additive early on). I switched to Mobil 1 at about 130K miles. The motor is still running fine. I also have a 1997 Z3. Oil changes average also about 12,000 mile intervals. The car has 140K miles. The engine runs perfect. My E90 has 75K miles, motor is strong as the day I bought it. I've averaged about 17,500 miles between changes. I am the original owner of all three cars.

what's your point? Looks like you changed oil on your cars at shorter intervals than advertised by BMW. So do I. And did run my first E30 320i for 360 kmls, the second owner put another 50k on it before crashing it.

I change my oil at every 20kmls. BMW system might tell you 40k will do, to me degrading oil will cause accelerated wear which typically starts to show itself way after the warranty period. I (now) run my cars for 4-5 years, 120-150 kmls total, and to me the additional oil changes is peanuts compared the knowledge of having good oil

This thread is only on what the ECU calculates, and at least I learned a thing or two. But I'll still change my oil at 20k as there's loads of other factors, and certainly with EGR on diesels.