[cmiovino]

I have a 2004 WRX that sees about 1500 miles/year. My BRZ sees more now at about 4-5k/year.

I used to change it every 6 months, but I've been going about a year. Haven't noticed any difference. It's only 1500 total, but there's a decent amount of idling and cold starting for winter when it's used more when the BRZ gets put away in the garage for 5 months.

Personally, I'd do yearly. It's not that expensive. Get an oil analysis done. My main concern would be water or fuel depending on how it's driven. I do them on the BRZ, but not WRX due to the mileage it sees now.