Originally Posted by chromisdesigns
I was just talking with my indy mechanic on this very subject the other day when I took it in for an oil change. He says their experience indicates it is total engine time, rather than miles related. He said they are starting to recommend pro-active changes at around 60K miles if you do a lot of city driving in an E9x.
That's good info, and makes a lot of sense as many industrial pumps and equipment use hours as the maintenance metric.
Changes at 60k feels a bit early for proactive replacement, but if you really don't want to be stranded it could be worth it. If I make it to 90-100k without failure, it will definitely get replaced.