I was thinking about trying 5w-20 in my truck just to see what would happen (lower mileage, less noise, etc), but if the thinner oil doesn't work, I don't want to just dump it out and waste it. I would like to just add something to make it thicker: Back to something near a 30 weight. I would like something that is actually a lube, and not just a thickener. I don't want to use Lucas. Maybe something from LubroMoly. It should also cost less than $6 since that is what an oil change would cost me.