Quote:
Originally Posted by carve
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.
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I used to do oil changes on my 330i every year before winter storage and the CBS would not adjust the interval after the oil change. It always stayed the same. The car took two years to get to my first service and I changed the oil two times before I had the dealer do it. The service still was at 25k KM.
Quote:
Originally Posted by mr.i
I'm going to adhere to the established recommended service interval and cut it in half. I've got a reputation around town for keeping my cars in above average condition and while I'm not sure who is putting the word out, my used autos fetch premium prices from both private buyers and my favorite dealer. That subtle peace of mind that I get from making sure my equipment is maintained to high standards is my personal decision. The rest is self explanatory.
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1/2 of the normal interval is a good interval IMO.
Quote:
Originally Posted by markinva
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. |
The one thing that I know is factual is that the CBS does not measure the condition of the oil. You can drain the sump and do an oil change and the interval remains the same as before you changed the oil, I know this because I have changed the oil on my BMW's and noticed the service interval was unchanged after the oil change.
Anyhow no matter how you feel about all of this, as a Mechanic I feel that the service intervals are too long...... I base this on teardowns of engines that have had regular maintenance at 8K KM intervals and ones that have had extended 16K KM+ intervals. One thing I can assure you is that you can easily tell the difference in the cleanliness and lower wear on the engines with more frequent oil changes. The damage/wear will not be noticed in the first 160K KM of the engine but will usually start to manifest itself there after.
I have said this in another thread, If you are not going to keep your car out of warranty follow their service interval but if you are going to keep your car for the long haul cut their intervals in half at the least. BMW and the other Manufacturers that use the CBS system or other similar system base the service intervals on engineers recommendations. I can tell you this for sure, engineers don't know it all. When we have a failure or issue on our heavy equipment at the mine I work for (Caterpillar 797 and Komatsu 930 Haul trucks) engineers from the manufacturers come looking and taking pictures and asking us for our recommendations and more times than not the mechanics help them with the redesign of the affected components by giving them their input. While engineers are very intelligent individuals nothing beats seeing something work in the real world and even better, seeing it fail and knowing why it did. Engineers know theory from behind a computer screen or from a sheet of paper and that is the problem. something can be engineered to work and be durable and look good on paper but in service it can fail right out of the gate.
I am not sure of your profession but my profession is a mechanic, (both automotive and heavy equipment) and I suggest you take some advice from someone who knows. I am not a doctor or lawyer so when it comes to medicine or law I seek their advice. BMW and other car manufacturers that are using CBS or similar systems have two things in mind profit, and environmental relations. From the profit stand point the less maintenance they do inevitably the more parts thay sell in the end after the warranty is up (or the less oil and filters they pay for in the event of paid maintenance) and from the environmental stand point the less waste oil they are producing.
To sum up; car companies are profit based and highly scrutinized organizations don't think that all of their motives are pure...... If I ran a business I would spend the least amount of capital I could to keep profit up while maintaining customer satisfaction...... I think this is what is happening BMW and all other manufacturers are walking the fine line of keeping the customer happy while maintaining a good corporate image and maximizing profits.