Quote:
Originally Posted by williamx5
Good day!!
I may get a lot of hate mail about this thought, but I only change items that are broken or have worn out... I don't wait for a tie rod to fail before replacing it... Obviously... But an oxygen sensor is one that won't get changed unless the computer is telling me it is time... I think some items BMW recommends on replacing at certain time or mileage limits is Preventative Maintenance to keep the annoying CEL or SES light from illuminating... The other items, like LTF is them getting out of replacing fluid... I don't believe any fluid is made so well that it will last 300,000 miles...
So, my vote is replace when it gives a code or performance degrades substantially...
Cheers!!
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I agree completely. Definitely don't replace the downstream ones until you get a code, at least.
I wondered same as the OP when I got my '01 3.0i at around 170k miles. Maintenance records indicated they were original (and subsequent removal seemed to confirm this), and even though the truck ran great, I hoped for better MPG and was grasping for solutions.
After research, I ended up replacing the upstream ones, with absolutely no change in anything other than a lighter wallet.
I noticed that the "universal" ones (where you have to attach the connection yourself) were the same for upstream vs. downstream. So, figuring the ones I took out were just fine, I saved them in case I need them for future trouble shooting, or to solder in if a downstream one ever fails.