Hi Bob-Tog, I made it here. first post...I have owned about 5 LPG fuled vehicles. I found that it did not seem to matter which engine oil I used or how the engines were re-built, they all used a little oil which was about a litre every 2000 miles at best. Due to the valve seat recesion problems inherent to gasious fueled engines the oil consumption along with using a medium to high ash oil like an off the shelf HDMO was likely good for the engine in the long run. Where I work there are several one ton crew vans that are LPG fueled and have over one million miles on the original engines. Anyone that has owned or operated a vehicle that is either LPG or natural gas fueled will tell you that the engine oil stays clean for thousands of miles. These vans I mentioned have their oil changed about once every 6 months or around 30,000 miles. In that time and distance the engines would have consumed about 15 litres of oil. In the aviation industry they call that self (oil) changing and is due to the run-loose engine specs of Lycoming, Continental and other brands of air cooled piston engines. The controversy about a high ash oil causing ring-zone deposits and cylinder bore polishing I think is a lot of rubbish. I had to take the heads off one of my V-8 LPG engines because one of the hardened seats dropped. This engine had over 100,000 miles on it and the cross hatch was still evident and visible. The reason (off topic) that aircraft engines specify an ash free engine oil is because they sit at one RPM almost their entire life which causes a distinct pattern in the combustion chamber deposits. The other reason is that if a spark plug fouls and the big air conditioner fails.......