Dear all, Enjoying the forum. Saw a few Subie owners' archived posts but wanted specific info: Vehicle is '02 US spec Impreza WRX, 2.0L turbo, ~4.5L oil sump, driven daily mostly on motorways, usually distances over 20 miles. Ambient temps range from 10C to 25C in "winter" and 20C to 40C in summer. Speeds are typically 65 to 85 mph, 2700 to 3500 rpm. Redlining and boosting in low gears isn't frequent but it's not completely unheard of... Moderately to mid-level dusty, low humidity environment (I live near farms). Air filter is Subaru, intake is stock, no modifications to vehicle at all. Oil filters are works Subaru from the dealer. 7,000 miles on odometer. First change at 3,000, second at 6,500, both dealer's dino oil. I'd like to switch to synth at the earliest advisable point. What mileage should I switch at? Archived posts suggest my motor breaks in over a rather extended interval. Is 10K OK for me? Or wait to 15/20/something else? What synth oil for me? Mobil 1's rep said "use our 5W-30 year round" but in the same breath said "we use no moly in our oils" which got me thinking, considering the analyses and messages posted here... Still, Mobil 1 is attractive since I can get small lots of SL stuff OTC, with a dated receipt for warranty puproses, and it's genuinely a good synth oil. Any turbo'd 4 owners or WRXers specifically running M1 SL 5W-30 care to share info? How about 0W-40, 10W-30, or 0W-30 for my application? Better/worse for wear? (Manual prefers 5W-30 but also lists 10W-30, 10W-40). I'd like 4,000 mile drain intervals (dust concerns and turbo temps) and my goal is longevity, not fuel economy or even power. 4K drains shouldn't be a problem with a normally aspirated commuter car and any SL oil theoretically, but my WRX isn't normally aspirated and isn't always strictly a commuter car - fellow owners will know what I mean. Looking forward to any info, thanks!