-SAE 30: This is a non-detergent oil, which is ideal for older engines. It provides good protection and does not contain any additives that could damage older seals and gaskets.
-10W-30 or 5W-30: These multi-grade oils are also suitable for use in classic engines. They offer better cold-starting lubrication but still provide adequate protection at operating temperatures.
-10W-40: This oil is a bit heavier and is suitable for use in warmer climates or with higher mileage engines.
It's important to note that GM, in 1966, recommended SAE 10W-30 oil for your engine. Your decision for which type of oil to use will depend on the specific needs of your engine and your driving conditions. Consult with a qualified mechanic or refer to the owner's manual for specific oil recommendations for your particular 1966 327 Chevy motor.
