I'm using BP2380, previously Mobil Jet 2, in C28 in Long Ranger, Now been using it for 500hr 2yrs, but difficult to quantify any change, except perhaps that it costs a lot more to buy, but any improvement will probably pay in the long run. I didn't go for Mobil 254 as nearly every RR 250 engine that I've seen using 254 seems to have more than the normal amount of oil leaks.