The engine has about 25,000 miles on it since rebuild. It does have one of those old style oil filters which I know are not the greatest. I don't think its pistons as it is a definite lifter clack. The oil is very clean but I think perhaps too thin. As mentioned when I pull the dipstick and hold it for a few seconds the oil drips off the end. Almost like no viscosity if that is the right term.
