I have participated in a few discussions on this forum concerning whether the 15K oil change interval recommended for new BMWs is adequate. I think it is fair to say that most owners voicing their views on this are skeptical and somewhat suspicious about such a long interval. After driving my 2004 745li for about 12K miles after its last oil change, I sent a sample to Blackstone Labs for an oil analysis. The results were shocking -- a lot of metals in the oil and total exhaustion of the protective oil qualities. So I concluded that perhaps those who warned that 15K was too long were right. Well, I have thought some more on this point. And the following occurs to me: 1. The longer the oil interval, the more metals are likely to accumulate in the oil, even if the oil is NOT failing in its ability to lubricate the engine. It seems to me that some metal will accumulate in the oil and the more time between intervals, the more accumulation. But that does not necessarily mean that the oil interval is too long. 2. The idea that the protective qualities of the oil are "exhausted" seems to me somewhat ambiguous in the context of an oil analysis. Not sure what it means. Certainly the oil will change in chemical composition over time. But the question is: What material effect will this have on the engine. The oil analysis assumes that the effect will be deleterious, and that is plausible. But at what rate? If I had kept driving the car to the recommended 15K limit, would that have made a significant difference in engine wear? So I would say my current frame of mind concerning these long recommended intervals is one of -- well, confusion. It is extremely wasteful and potentially harmful to the environment to change oil too frequently, and it is harmful to the engine to delay changing it when the oil needs changing. But I am not sure the oil analysis is the definitive test I thought it was. Interested in other views on this subject.
I am not sure why you would be confused. With the additive package being exhausted, the oil's capacity to lubricate and protect is near worthless. That would have been alarming to me and I would have been running out to the garage to change the oil (assuming that I would go out to 12K miles without an oil change to begin with). Further, the metals in the oil are not surprising. The oil filter is designed to capture as much of this as possible. But, if the interval is extended, how can you expect the filter to do its job over this period of time as well? I would guess that the degradation in the oil and the filter's capacity to protect goes down exponentially at some point. Rather than expend a lot of energy figuring this out, why don't you accept the analysis that you paid for and change your oil more frequently? It simply confirms for me that the intervals that BMW has set since they moved to providing service with the new cars is simply too long. Your analysis shows exactly that.
What I am confused about is this: 1. The amount of metals in the oil will increase the longer the oil is in the crankcase. If you analyze the oil after 1,000 miles it will have much less dissolved solids than after 7,000 miles. But that does not mean you should change your oil after 1,000 miles. 2. The amount of active additives in the oil also degrades over time, just as the amount of metal accumulation increases. But at what point does this pose a danger to the engine in terms in increased wear? It seems to me that the only real way to categorically determine the optimal oil change interval is to directly measure engine wear at various change intervals. I have heard people say that the longer oil change intervals (15K miles) were introduced in conjunction with the free maintenance program, the implication being that BMW is just trying to save money on the program at the expense of the longevity of their customers' cars. Well, the longer intervals are recommended for BMW cars sold in Europe, and there is no free maintenance program there. And would BMW really risk customer good will in this way? I will be changing my oil more often, but I think the oil analysis results leave some open questions, as described above.
You are probably correct on your comments, but I would say this... The additive packages included in the synthetic oils offered today are superior to the additives of mineral based oils of say 15 years ago. But, the engines are performing better today as well. We expect 8,000 RPM and 333 HP out of our E46 M3s. We expect 8,400 RPM and 414 HP out of our E92 M3s. Compare that to the E30 and E36 M3s which produced much less RPM and HP numbers and had much shorter oil change intervals and ask yourself the same questions. The synthetic oils might be good, but they are not that good. The oil analysis that you paid for said quite a bit. I am simply suggesting that you listen.
Good points. Thanks. I'm going to a 7.5K change interval per Blackstone's recommendations for my 2004 745li and will post the results of the analysis at both 12K and 7.5K miles.
Good discussion guys! I am going to have my oil analyzed by Blackstone at 7.5k and again at 10k just to see what the results are. I shall keep everyone posted! (fyi...I am only at 2k right now )
I have had the same concern, have a 2008 535I at delivery the oil change indicated 13,000. now at 10,000 miles of highway driving in 2 months it indicates 8,000 til the change. I contacted the dealership, they state that 16 - 18,000 miles is normal. we will change at 10,000.
Filter What about the condition of the oil filter after such a long interval? I have 16,800 and thankfully my one year is coming up next week. I don't think I am going to wait another 17k for an oil change. We have a Lexus and they recommend 7500 per service. That seems more realistic - especially considering we live in the New York tri-state area with a lot of stop and go as well as winters.
oil change Interesting, I spoke with a BMW tech away from the shop concerning oil change intervals etc, his reply makes sense , he states that BMW is only concerned about the original owner, usually keeps the car for 50,000 them sells it, the damage from extended time between oil changes catches the second owner.
I really hope that isn't true but I can see BMW doing that to save on maintenance costs. Then again, BMW has the same recommendations in Europe as well where they don't pay for service. Most BMW's in Europe are purchased and not leased. Does anyone know how the BMW filter is different from another high quality filter?
