Last time I was at the Isuzu dealership I spoke to the service rep and she showed me a bulletin from Isuzu that said it is perfectly normal for these engines to burn oil as it is part of the design to keep all seals lubricated. It also says in the owner's manual that it is the owner's responsibility to check and top off the oil every other fuel fill-up. If it's in the manual, I'm guessing it's not a design flaw. There are other engines out there (VW 2.0, Wankel rotary) that burn oil as part of the design. Just my two cents.