I have a .56 that will run more than 15 minutes on 8 oz of 15% Omega. My .72 will run almost that long too on same fuel and size tank. I have a .82 still in the box.

Maybe you need to recheck your low end setting. Maybe the HS too. I ran my .56 for a long time thinking it was a hog until I found out that I had peaked the HS in a null area. RPMs dropped, so I thought I had it peaked. I finally decided to see how lean I could get it since it was burning fuel so fast, and I ended up almost another turn in to peak the engine. I've heard that some engines have the same sort of spot that will fool you.