Originally Posted By: grease_monkey
upside to synthetic oil: better lubricity properties, has higher resistance to breaking down, most synthetics like mobil 1 have high detergent content which means a cleaner engine
downside: it is thinner than conventional which means if your seals are slightly worn it will make the leak even greater. if it is being used in a high mileage it can also burn off faster than snake oil.
My facts are based on experiences. A good Snake oil is castrol GTX and a good synthetic is mobil!
hope this helps
Now with 259,000 miles on my Civic, using the SSO, it burns no noticable oil. The sump is full when I change it at ~3,000 miles.
This wasn't the case when I used Castrol 5W-30 GTX, I could count on burning through a quart or so in those 3,000 miles.