Xoutpost.com - On average, how long does X5's automatic transmission last? Does anyone need to repla

There are two very different questions in your query, with two different answers.

1) How long does the X5 transmission last until it wear out, ie it is used up? A long time. There are examples of 300,000 mile transmissions, so the vehicle doesn't have a transmission that wears out early. The thing about wearing out is that you can look at when they wore out, and plot it on a graph. You would see a grouping, ie a common point at which many were worn to the point of needing overhaul. This isn't the case with the X5. People talk about 100,000 miles, but I don't see any correlations that support that being a common failure point, other than it is more than 0 and less than 200,000.

2) How long does the X5 transmission last until it breaks, due to a random event of a minor (or major) component? Not long enough. There are a wide variety of failure modes seen with these transmissions, and they are so random that some have failed at 30,000 miles and others never. The problem with these types of failures is that you can't compare them in terms of mean time to failure (MTBF) because they are all over the place, there is no consistency. That also means that one person's experience isn't particularly helpful in forecasting what will happen to another person's transmission.

As an aside, I believe that the biggest driver of failures in category (2), above, is complexity. These machines are more complex than they need to be, and that results in random failures. Sad but true.

If you do a search, you will find many other threads where posters have tried to find an average life, believing that (1) is the predominant failure mode.