Preventive AOS replacement
 

I recently purchased a 2001 Base that appears to have an AOS that's been there for some time. Is it worth replacing it as a preventive measure or just wait until it fails? The car seems to run really well minus needing a motor mount. No excessive oil in the intake that I saw when I cleaned the TB, but there was definitely residue. I did not measure vacuum on the crankcase though.

It is one of those items that when it goes you could be stuck. I bought one, cared it around with me on road trips for a year. Then finally changed it as preventive. Original never gave my any trouble. Unfortunately, it is not uncommon for a new AOS to go bad right after install. Because it was of poor quality new. I have been lucky with my new AOS so far.

I too have an '01 base that I purchased without any service history about a year ago. I drove it for 6-8 months then had IMS, RMS, clutch and AOS done all at same time. More piece of mind. Plus I've seen a handful of AOS blow during autocross events and didn't want to do that.

for street driving, I would replace only when you start to see signs of failure. If you track it, might be worth swapping it out.

I'd do it when any other engine work is being done as part of the "while I'm there, might as well" philosophy.

This is the answer! They ain't making them like they used to. While the 986 was in production AOS were tested before installation & any that failed the test were returned to the manufacturer. I buy from the dealer when it fails so you get a 2 year warranty on the best part available.

This is why I buy as many parts as I can from F.C.P Euro. Lifetime warranty on ALL parts.