Is it possible oil is getting into #7 cylinder from headgasket. Engine burns oil from left pipe only ,#7 plug oily . When it smokes it's bad at idle . SOME times it doesn't smoke at all. never smokes at start up. Oil returns seam clear. Compression test apx.120 in all cylinders but I forgot to block open throttle. Vacuum gauge reads steady 20. I'M waiting on leak down gauge that's still on backorder. When engine is running it's smooth. No pressure in oil fill when running. It does have pcv valve and it's new , also oil cap is plumbed into air cleaner . OIL pressure was 60 lb when cold with 15w 40 , I tryed 20w 50 and pressure is 80 cold. Pump is new within a year. Smoking problem didn't change with thicker oil.

62 f100 short unibody 292 big back window massachusetts