Good quality dyno oil.. Change it by months not mileage... If car is not using oil, just keep oil clean...The most expensive synthetic gets just as dirty...2cts
I don't want to start a debate but I would stay clear of synthetic and use good old fashioned motor oil. As suggested, change it by time. Not to scare Todd, but low mile 40 or 50 year old engines can be prone to failure, based on my experience.
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1966 Strato Chief 2 door, 427 4 speed, 45,000 original miles
1966 Grande Parisienne, 396 1 of 23 factory air cars
The guy who build my 66 283 said stay with 10W30 and don't use any of that new synthetic or lighter oils. the old engines like the good old standby. i do mine every 3 months. including it goes in storage with fresh oil and a fresh change when it comes out. there is still moisture in the motors while they are being stored and the oil soaks it up.