1972 Plymouth scamp 318

Congrats on a nice purchase! Mobil 1 15-50w has extra zinc and is full synthetic. It is only 27.00 (5 qrt jug) at Walmart. You would only need to change this once a year if you put 5000 miles or less on your new ride. Some do use regular conventional oil with a zinc additive. Just so you know, the only thing you are trying to protect is the cam lobes. Most cars around 1986 or newer had roller cams, and the zinc isn't necessary. Your motor (assuming its original) has a flat tappet cam. Usually, though, the mopar cams were amoung the best and so long as it has 50k or better for mileage, you could even run Quaker State Defy oil of the weight of your choice. This oil has a little extra zinc and is a synthetic blend. Walmart sells this for 16.00 for a 5 qrt jug. I called Valvoline tech department once and they said usually even straight up conventional oils are fine so long as the engine is well broke in (50k plus mileage). It's new flat tappet cams that are in a world of trouble with conventional oils.