Must have been around 1977 (I was 17 at the time). My father had a customer that brought in his '62 Catalina, 4-door HT and gave it to him. Dad didn't want it but took it anyway; you now that thing about not wanting to insult a gift giver. It was a heavy oil burner and had a noisy valve train. Dad let me work on it in my spare time.
The first thing I did was pull the valve covers to see if there was any worn out rockers, etc. As soon as I pried the first VC off the head, I hear a huge splash of liquid on the floor. The oil returns were so plugged up that the oil was filling up the VC's.
I unplugged the returns, did the oil and filter (several times; no synthetic back in those days), replaced some of the worn out rockers with some decent ones I saved from my '63 Bonneville rebuild, and ran it....every afternoon after school I just let it idle for 2-3 hours. That engine was so plugged, the exhaust system would drip oil out the tail pipe.
First time I drove it, I took it out at night on the highway. It produced a smoke screen that Seafoam only wishes it could. Smoke and little bits of sparking chunks. I was afraid it would start a fire.
Once all the oil was burned out of it, it ran for another 3-4 years. I sold it to a classmate of mine for $265. It met an untimely demise in slow speed head on.