I've decided to daily our 2005 Impreza Outback sport on my 80 mile round trip commute. I really enjoy the car, so I'm letting my wife drive our newer Impreza sedan that has been my daily commuter.

 

The car seems solid running at 150K miles (we've had it since 129K miles). I know the EJ253 version of the EJ25 engine series is more known for oil leakage from the headgaskets than anitfreeze leakage. There is a slight amount of oil seepage on our car, but nothing amounting to to an oil drip, so I think there is time before headgasket replacement.

 

I'm wondering how many miles have people gotten out the EJ253 (2003- 2007 vintage Subaru's) as compared to the older engines. I know EJ22's are good for 300- 400K miles, and even some EJ25D's that didn't succumb to overheating are going over 300K miles. If I wanted to drive this car for another 5 years, could I expect to get 300K? (assuming I continue 3,000 mile oil changes and continue to drive like a grandma)

yes, no overheating or compromised oil and the blocks are good for 300k.

 

fuel pump and alternator are most likely culprits to strand you.  replacing them with OEM is expensive but good 150k insurance for "like new" reliability.

 

adjust valves to mitigate burnt valves

replace all timing components to avoid timing pulley/tensioner/belt failures

reseal oil pump/cam seals, water pump because it's easy while replacing timing gear. 

We did the timing belt. tensioner. idler pulleys/ water pump at 129K when we bought it. I believe he resealed the oil pump too (retorqued oil pump bolts).

 

I wasn't sure if this motor has hydraulic or mecnanical lifters, so if they are mechanical, what is the mileage when they should be adjusted?