Engine oil Mobil or Castrol

Mobil1 V-Twin 20W-50 in all three holes.

I heard you can throw 20W-50 (Synthetic, specifically V-Twin Mobil One brand) in all three holes and have no issues.

My rotary expert in north Texas recommended that I use 10-30 conventional oil. I personally prefer Castrol GTX

I use Castrol Synthetic 10w-30 on mine.

It’s thicker oil, so I feel like it gives the engine better protection. With 272k miles on it, I figured why not.

Mobil1 x1 1000 15w40 in all my cars. My engines are clean and quiet, oil pick-ups don't clog, there's a nice permanent oil coating everywhere.

I’ve been running Castrol GTX 10w30 conventional in my 9000 Aero. Brought it to a Saab specialist and he recommended it. Need to have the valve seals redone and the oil is thick enough that it doesn’t get past the seals and no smoke. No issues running it. I change it every 3 months regardless of how far I’ve driven.

I'm apparently the least informed person here (never done an oil analysis), but FWIW I seem to be fine with Mobil-1 0w40 on a 996.2 with 208k miles.

Mobil 1 5w50. Temperate climate. Car always garaged. Annual changes at 4000 miles. Zero top ups required.

Castrol Power 1 isn't a bad oil, but I'd say not the best either. I have only used LiquiMoly as an alternative, so far and I rate is better than the Castrol but it did cost almost 2x as much too.

I used to use M1 0-40 in my VR6 Corrado, but the valve, chains and engine noise went way up, especially at a cold start