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      05-08-2009, 08:56 AM   #1
markinva
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The enormous amount of misinformation about BMW's Oil change intervals

This stuff spreads like wildfire. I've seen these statements a million times on throughout BMW forums:

-The oil change monitor doesn't evaluate the actual oil life remaining, it just uses the amount of fuel used, engine temps metrics etc. The Condition Based Service (CBS) interval is not sophisticated enough/reliable.

-The Maintenance intervals proposed by BMW will get your car through warranty period, but after that get ready for massive repair $$$.

-BMW went to extended (15k) intervals based on the oil change monitor only when and because they started paying for maintenance. The intervals are only that long because BMW wanted to save money/they are paying for it

Is there one shred of evidence for any of the three above "facts"? People routinely say this stuff on every bmw forum I've been on, yet it's all theory and speculation. Not only that but it is weak theory and weak speculation.

Consider:

-Thousands of people have been using the normal CBS for years, and you don't see BMW engines grenading very often. Many times more people stick to the CBS than those that don't. Thousands of people have gone 100k+ miles on the CBS intervals as they have been used for many years.

-The CPO program would be an utter disaster if the oil change intervals were too long, as these more used BMWs would show lots of signs of engine trouble and cost BMW $$$ in CPO repairs.

-BMW's around the world come with the SAME CBS oil life system- and yet the USA is one of the ONLY countries in the world where maintenance is covered. You really think BMW would threaten their worldwide reputation, engine reliability and CPO programs in every country in the world, just because maintenance is covered in the USA for four years?

-The condition based service does measure oil quality- at least at some level. Please look at the pdf file on post #3 for some evidence.
http://forums.bimmerforums.com/forum...d.php?t=954499

-BMW is not the only manufacturer to rely on CBS, porsche, mercedes and others do it too.

Please note that I have absolutely no problem with those that want more frequent oil changes- heck I am seriously considering getting the tischer kit and doing my own oil changes in between intervals. That's not my point here. My point is that there is massive missinformation that gets repeated on here and people need to be made aware that it isn't factual.

Last edited by markinva; 05-08-2009 at 09:24 AM. Reason: Post #3, not Page 3
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      05-08-2009, 09:04 AM   #2
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      05-08-2009, 09:11 AM   #3
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Not to start a flame, but look what happened with Mercedes in 2001 with the 3.2 6 cyl engine and sludge, Lexus around the same time and Audi again the same problem. Not a shot I would go 15K without a change. Yes the oil might be fine but wht about the filter?
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      05-08-2009, 09:14 AM   #4
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good information but why so angry???
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      05-08-2009, 09:16 AM   #5
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Quote:
Originally Posted by island111 View Post
Not to start a flame, but look what happened with Mercedes in 2001 with the 3.2 6 cyl engine and sludge, Lexus around the same time and Audi again the same problem. Not a shot I would go 15K without a change. Yes the oil might be fine but wht about the filter?
yeah, these stories are scary. Shows what can happen. Again, I'm not saying 15k is the only proper interval. I'm not saying that 7.5k is too often. If you want to do it more often because you don't want to risk anything, great- I totally understand that.
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      05-08-2009, 09:17 AM   #6
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+1

OP, people do it for peace of mind.

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good information but why so angry???
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      05-08-2009, 09:18 AM   #7
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Quote:
Originally Posted by Curt2000 View Post
good information but why so angry???
Sorry- I didn't mean to come across as angry.

It's a pet peeve of mine when people spread rumors on the forums- well not necessarily the spreading of rumors, that's fine, I just hate it when rumors are presented as facts.

doing it for peace of mind is fine. Doing it because you think BMW is being chintzy and your car will break at 40,001 miles and the CBS computer is a dummy screen is ignorant.
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      05-08-2009, 09:19 AM   #8
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There is only one page in that thread. You can't view the PDF unless you're a member. Why don't you repost it here?

The oil condition sensor measures the conductivity of the oil. That may tell you how much water or metal shavings are in the oil, but not much else. Go ahead and change your oil on your own and then tell me if the computer lengthens the time until it says you're due for your next change (hint: it doesn't!). Based on this (admitedly limited) evidence, it's reasonable to infer the sensor is more of an "oh crap- the oil is all messed up and contaminated even though we predict it should have more life left based on our algorithms" device than something that actually measures oil condition to any degree that'd tell you when it needs to be changed.

Furthermore, The N54 is under a lot more stress than NA engines, and the tight tolerences in turbos are very demanding on oil quality. Oil that may still be "good enough" for an NA engine is not necessarily good enough for the N54, yet the change intervals appear to be the same.

The recomended intervals may get your engine (although maybe not your turbos) to 100k, but that's not considered very many miles these days. A-N-Y car available in the US should have no problem reaching those miles on the recommended maintaince schedule.

Last edited by carve; 05-08-2009 at 02:20 PM.
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      05-08-2009, 09:21 AM   #9
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Quote:
Originally Posted by markinva View Post
Doing it because you think BMW is being chintzy and your car will break at 40,001 miles and the CBS computer is a dummy screen is ignorant.
50,001 miles, unless I'm misinformed. That's when they asplode.
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      05-08-2009, 09:23 AM   #10
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Quote:
Originally Posted by carve View Post
There is only one page in that thread. You can't view the PDF unless you're a member. Why don't you repost it here?

The oil condition sensor measures the conductivity of the oil. That may tell you how much water is in the oil, but not much else. Go ahead and change your oil on your own and then tell me if the computer lengthens the time until it says you're due for your next change (hint: it doesn't!)

Furthermore, The N54 is under a lot more stress than NA engines, and the tight tolerences in turbos are very demanding on oil quality. Oil that may still be "good enough" for an NA engine is not necessarily good enough for the N54.
Have you considered that the oil condition sensor has more than one variable- ie time, mileage and condition sensors? Would it make sense that BMW would say, let's just measure the conductivity of the oil, and if that's good, let's tell owners the oil is fine... we don't need to worry about mileage and time?
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      05-08-2009, 09:25 AM   #11
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Quote:
Originally Posted by carve View Post
There is only one page in that thread. You can't view the PDF unless you're a member. Why don't you repost it here?

The oil condition sensor measures the conductivity of the oil. That may tell you how much water is in the oil, but not much else. Go ahead and change your oil on your own and then tell me if the computer lengthens the time until it says you're due for your next change (hint: it doesn't!)

Furthermore, The N54 is under a lot more stress than NA engines, and the tight tolerences in turbos are very demanding on oil quality. Oil that may still be "good enough" for an NA engine is not necessarily good enough for the N54, yet the change intervals appear to be the same.

The recomended intervals may get your engine (although maybe not your turbos) to 100k, but that's not considered very many miles these days. A-N-Y car available in the US should have no problem reaching those miles on the recommended maintaince schedule.
can I post attachments here?
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      05-08-2009, 09:37 AM   #12
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Quote:
Originally Posted by markinva View Post
Have you considered that the oil condition sensor has more than one variable- ie time, mileage and condition sensors? Would it make sense that BMW would say, let's just measure the conductivity of the oil, and if that's good, let's tell owners the oil is fine... we don't need to worry about mileage and time?
No- the oil conditions SENSOR only measures conductivity. Read my post again. The other things, as I mentioned, are part of an algorithm that PREDICTS when the oil SHOULD BE degraded to some level considered unacceptable.
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      05-08-2009, 09:41 AM   #13
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Quote:
Originally Posted by carve View Post
No- the oil conditions SENSOR only measures conductivity. Read my post again. The other things, as I mentioned, are part of an algorithm that PREDICTS when the oil SHOULD BE degraded to some level considered unacceptable.
I'm referring to your statement about why the computer doesn't adjust your time/mileage

I'm saying that the algorithm is telling you to change your oil (ie the mileage till service won't go up) when you put new oil in, despite the condition sensor saying the oil is ok.

And how are you an expert on what the oil condition sensor measures?

Aren't you speculating?
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      05-08-2009, 09:43 AM   #14
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Quote:
Originally Posted by markinva View Post
yeah, these stories are scary. Shows what can happen. Again, I'm not saying 15k is the only proper interval. I'm not saying that 7.5k is too often. If you want to do it more often because you don't want to risk anything, great- I totally understand that.
Every 5k miles on the dot. No sludge = happy 100k plus engine.
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      05-08-2009, 09:49 AM   #15
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any new car, either with free service or not, i like to change it in within 1k miles or less the first time around - but that's just me - i do it myself and it's cheap insurance.
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      05-08-2009, 09:53 AM   #16
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Ok, I uploaded the BMW pdf file about the oil change monitoring system.
Attached Images
File Type: pdf oil-sensors[1].pdf (81.1 KB, 3403 views)
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      05-08-2009, 09:54 AM   #17
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Quote:
Originally Posted by markinva View Post
I'm referring to your statement about why the computer doesn't adjust your time/mileage

I'm saying that the algorithm is telling you to change your oil (ie the mileage till service won't go up) when you put new oil in, despite the condition sensor saying the oil is ok.

And how are you an expert on what the oil condition sensor measures?

Aren't you speculating?
Reread my post. My point is, it's all based on the algorithm unless the sensor detects a LOT of conductive contamination in the oil. This would include metals and maybe water with dissolved ions, but it wouldn't include anything about silica (dust) or anything about the lubricity or viscosity of the oil. Many people, I think, are under the impression that the sensor is like an oil analysis lab in their engine.
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      05-08-2009, 09:58 AM   #18
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please tell me what this

Quote:
Originally Posted by carve
Go ahead and change your oil on your own and then tell me if the computer lengthens the time until it says you're due for your next change (hint: it doesn't!)

has to do with this:

Quote:
Originally Posted by carve View Post
Reread my post. My point is, it's all based on the algorithm unless the sensor detects a LOT of conductive contamination in the oil. This would include metals and maybe water with dissolved ions, but it wouldn't include anything about silica (dust) or anything about the lubricity or viscosity of the oil. Many people, I think, are under the impression that the sensor is like an oil analysis lab in their engine.
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      05-08-2009, 09:58 AM   #19
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Most of our cars are in the 40-$60k range. So I don't understand why some people just refuse to spend the $60 and do their own oil changes every 5k miles. It really takes about 10min to change the oil on a BMW. If you can afford the car than you sure as hell can afford to spend the $60 every once in a while.
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      05-08-2009, 10:04 AM   #20
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What I don't understand is how the hell can BMW claim that the N52/N54 engine can be driven for 15k miles without an oil change. In all the previous BMWs that my friends and family owned the oil change interval was about 5k miles. So what kind of magic did BMW put into the new engines? In the end it all comes down to simple economics. BMW is paying for your oil change so they want to stretch out the intervals as much as possible.
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      05-08-2009, 10:04 AM   #21
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dude, that pdf proves exactly what carve said; the sensor measures the conductivity of the oil, take that value and 'sent to the engine management system. The engine management system uses the signal for internal calculations.."

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Ok, I uploaded the BMW pdf file about the oil change monitoring system.
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      05-08-2009, 10:05 AM   #22
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My SA informed me that BMW is moving towards 37K intervals (60K in Canada)! They are using the 15K (25K CDN) intervals to ease people into the higher mileage intervals, they don't want to "scare" people. It seems as if that plan has already failed! I change the oil in my G35 every 12K with synthetic oil and have 140K on the odo with no problems. It'll be interesting to see if what he said is factual or purely speculation. I will say that with all of the oil consumption problems I don't see how this could be true.

Personally I have no problem with the current interval time frame. I strongly believe that the turbos would fail prematurely if the oil wasn't in good condition. We'd be seeing alot of 335's blowing smoke out the tail pipe, even with low KM's, and even more with sludge problems but I guess only time will tell. I also agree with the statement above about the CPO warranty and BMW's reputation, so until I see further evidence that damage has been done due to long intervals I'm going to keep on .
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