I have the same problem - have to add oil every once in a while (1999 Ironman) I use 10W30 Quaker State 4X4 semisynthetic. I was thinking that if I were to use Mobil it will be better but out of fellow members comments I see that they have the same issue using Mobil.
It seems that engine "consumes" more oil on highway.. but again maybe it is just an impression because in the city miles are accumulated slower then on the highway and speeds are lower.

Good concern - why Isuzu did not call back models which are affected by this to fix the problem. This SUV should not consume any oil !