Originally Posted By: BrocLuno
Depends on the motor... All carb'd and big cam, conventional because you'll have to change it before the synthetic offered any real advantage due to fuel dilution.
Lightly modd'd OEM engine, maybe a synthetic and two year change interval, but why...
Track car that see high heat, synthetic all the way.
Motor that sits for weeks at a time, conventional because true real synthetics have reduced surface tension and have a well documented "drain-off" phenomenon that will leave a thin oil film to cushion on restart. Dino oils will maintain capillary fill longer and thicker.
My car is a heavily modified fuel injected engine. Large cam, ported heads, high compression, etc.
But as far as my driving habits, it usually gets driven once or twice a week in the nice months, and a day at the drag strip once a year.