Castrol Classic Oils
The latest engines are getting smaller and more powerful all the time, and manufacturers are specifying complex full synthetic oils to cope with higher engine pressures and meet fuel efficiency targets.
If you're driving a muscle car or a European import, the manufacturer may well specify a fully synthetic motor oil. Alternatively, if you're driving an older domestic vehicle, the manufacturer may recommend a conventional oil. However, even though that's the most economical option, a full synthetic will almost certainly look after your engine better.