I have tried many oils in my Jaguar s-type 4.0L (GC, amsoil xl 5w30,valvoline AC,mobil 1, etc)but so far I think I like this oil the best. No uoa on any of the oils I have used but this oil seems to smooth and quiet the engine the best. The gas milage seems a tad bit better as well. I used the blend version of maxlife and will try Syn version next if I can find it. Engine also seems more responsive.