Personally I wouldn't since it is more pure than crude, and there may be issues with leakage internally and externally. Not saying there will but there is the possibility. Depends on many different variables such as mileage, age, condition, etc. Ultimately it's your call. If anything I would go with a blend or high mileage oil depending on miles.

Most of time the front and rear crankshaft seals can leak if the engine is very old. Not always but there is that chance. Synthetic oil in a real old engine is a little to late and will gain you nothing in the life span of the engine. I have taken apart many 2300 Lima engines and they all had the same problem. The crank and rod bearings are showing copper at around 100000 to 150000 miles and the valve stem seals are hard and wore out big time. The new engines made today will go 300000 miles if you treat them right. The engines made in the 60's and 70's will not. Changing the oil is more important than what kind of oil is used. I change oil in all of my cars at 3000 miles. Cheap insurance for sure.