Engine oil IDEMITSU or OEM Subaru

I've been running Idemitsu oil in the XT and the wife's Crosstrek for the last four and five years and have been happy with it.

You’ll be fine, idemitsu is a bit of a rotary specialist when it comes to fluids

Yes, it is good advice. When a new engine is breaking in, there is a lot more wear metals. It's not uncommon to see metallic flakes or shimmer in the oil during your first oil change. Parts wear/bed in. That's why there is a break-in period on almost, if not all new cars.

I did my first oil change at 1k miles on my BRZ; I saw a lot of metal shavings come out of the oil. The oil also had a metallic shimmer to it. This is totally normal, but I want to get rid of all of that so it is not circulating around the engine post-break in period.

I think Idemitsu is the better option if you have access to it. Mostly because it was developed for the rotary engine.

My '15 Forester will burn a quart of oil every 1000 miles if I run 0w20.

I switched to 5w30 and it's all good for 5000 miles

Idemitsu to both, because it’s designed and tested on rotaries.

I use idemitsu rotary 20w50

I stick to Idemitsu. I have a Sohn adapter fitted, so it's 10-30 Idemitsu in the engine, twice a year and Idemitsu Premix in the Sohn adapter and in the fuel tank.

Well, some manufacturers do have way shorter oil change intervals than Euro manufacturers. The Subaru severe driving interval is 3000miles/6 months, and I do lots of short trips in a desert climate so I usually try to be around 3-4000 to stay on the safe side for warranty and whatnot.

Having had multiple Subarus that leak oil like crazy (they all do when they get old) the leaks are most likely too much for the stop leak additive to fix anyway.