I ran Valvoline 10w-40 hi-mi in my '83 Delta 88 winter beater (sold to a friend). It used maybe a 1 qt/3500 mi, but when I switched to the hi-mi oil, never used a drop --

My latest winter beater (Grand Marquis) uses 1qt/500 miles, but mainly due to bad valve cover gaskets.

I know it does smoke due to valve stem seals (typical 302), so after I redo the valve cover gaskets, I'll give the hi-mi oil and try.