Quote:
Originally Posted by sunny5280
So with everything you said you couldn't point me to one piece of evidence?
Look, I'm not saying there is absolutely zero risk with replacing the fluid. As with anything there is a risk. I have repeatedly acknowledge there is some risk. And, like JCL, I feel that risk is slight (that is his qualification, not mine).
As for my guy he owns his own business and has been doing transmission fluid changes for years. I think he's more than qualified to have an opinion on the subject.
Also stating fluid changes have benefit is not the same as saying you will never have a problem with the transmission. That would be akin to saying that changing your engine oil will result in zero problems with your engine. I don't think any of us would say that...do you? So why would you make the same argument with transmissions?
Perhaps if you explain why new transmission fluid is likely to dislodge sediment whereas old fluid will not maybe I could see the risk changing from slightly to a more likely possibility. Can you do that?
JCL also alluded to thinner fluid and improperly performed fluid replacement. Perhaps the issue has more to do with incorrect fluids or work being performed than it does with merely doing the work. My assumption is the correct fluids being used and the work being done properly.
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I am not sure what type of proof you are looking for? What will it take? Mike Miller is the technical editor for BMWCCA's Roundel magazine. The BMWCCA has over 80,000 members. He answers up to 50 technical questions per day (according to himself) and about 3-5 pages make it into the magazine every month. He is also a contributing editor for Bimmer magazine where he answers additional technical letters. I think he did, or currently does, the same for European Car as well. Basically, I am saying that his data base dwarfs your mechanic's. Therefore, he should be better able to analyze trends, especially where BMW's are concerned. Like I said before, I wish I could post the entire PDF, but I cant. In it, he states very clearly that he has seen all too many times where where a well-meaning owner or technician performs an ATF and filter service on a neglected but well-shifting automatic, and then all of the sudden it starts slipping. He goes on to say that he feels a contributing factor of this is
that the fresh ATF flushes a bit of sludge from a place where it was doing no harm to a place where it does do harm. He also see's overfilling, underfilling, and cleanliness as issues.
He also goes on to say that the fluid in BMW's "lifetime fill" automatics is proprietary info and highly recommends that the a dealer performs this service as no one knows exactly what BMW's proprietary ATF is. As I pointed out before, he states that not even all dealers will want to touch the trans fluid, not just typical shops that are buying into the "urban legend" as you say.
You don't have to take my word for any of this. Become a BMWCCA member and you can have access to the full article in no time. I am glad that you are finally realizing the risk is real and is not simply an urban myth as you said multiple times before.
Also, with some BMW automatic transmissions seeing 200k+ miles on the original fluid (think we have a few here) as well as the dime a dozen 100k+ on original fluid here, the fluid itself is no the main concern. Like JCL has said, the other components are going to fail before the fluid and changing the fluid every 30k miles is not guaranteed to make the trans last any longer.