00-04's leak externally - so as you're buying you simply want to do the following:
1. assess if there are any current leaks
2. assess if they've ever been replaced before. 00-02 were under an extended Subaru headgasket recall (additive only) and warranty (100,000 miles) campaign.
3. change the coolant and add Subaru's required coolant conditioner immediately
4. make sure the engine is in good operating condition, tune up, no shaking, electrical system clean and sharp
*** If #2 is an affirmative then it would be nice to investigate what gaskets were used, if the heads were resurfaced, and if Subaru's conditioner was added.
However, I'm trying to get a feel for around how many miles the original head gaskets seem to be going out in these cars.
Anyone else have some input? I know a lot of guys have had the HG's go out, so how many miles did the car have the problem showed up?
there is absolutely no mileage relationship with Ej25 headgasket failure.
They were failing at 30,000 miles under warranty when they'd rarely show up in public forums like this.
Subaru offered a 100,000 mile extended headgasket warranty on 2000 - 2002 EJ25's - that can be interpreted multiple ways, but for them to take such an approach suggests early failures were prompting the need for customer confidence in that engine.
when mileages are given, like 120k, they are really just making a statement about the average mileage of most 00-04 cars that are on the road today, which is just what people see the most of. 10 years old, average yearly mileage of 12,000 and WALLA - you have 120,000 miles! amazing! the mileages are irrelevant and hold no value in ascertaining your purchase in regards to headgaskets.
or mileages represent a given persons experiences or the means through which the information is "seen" - the average mileage of those that hit the boards, their friends had, get worked on by DIY's, show up on craigslist, etc. lower and higher mileage cars aren't as likely to land on the radar screen due to lower mileage cars being more likely to get repaired off the radar screen because they have higher value, as well as higher mileage cars being more likely to end up as craigslist specials or sent to the scrap yard.
failed EJ25 headgaskets have come to me that were repaired at 30k and were leaking like sieves at 300k but never replaced.
if one can't sift through conflicting anecdotal experiences - just go look it up yourself. headgasket failure logs affirm that there's no mileage to assign to EJ25 headgasket failure:
you can also scour craigslist and find gobs of blown Ej25's with all sorts of mileage on them.
there are forces at work that would even make an average of those mileages inaccurate, but nonetheless they show gobs of low mileage failures and put to death the idea that a statistically relevant mileage can be assigned to EJ25 headgasket failure.