New Mickey
The user formerly known as mickey
AAA has confirmed what high performance engine manufacturers, including jet engine makers, have known for decades: Synthetic is better. Way better.
Personally, I won't put conventional oil in my lawnmower.
The only application that I now of where synthetic oil is specifically DISAPPROVED is in piston general aviation aircraft engines. Companies like Lycoming and Continental forbid the use of synthetic oil, though semi-synthetics are approved in some applications. Why? I've been trying to find out for years, and the closest I've come to a definitive answer is that synthetic oil doesn't get along with the high levels of tetraethyl lead that's still found in aviation fuel. (Though I find the explanation a bit weak.) Personally, I lean toward the theory that pilots are just extremely conservative.
One of the benefits of synthetic oil that's often overlooked is that it has much better viscosity stability across a wide temperature range than conventional oil, and thus needs considerably less Viscosity Index Improver. For example, a 5w30 synthetic doesn't need nearly as much of that chemical additive as a 5w30 conventional. The Index Improver chemical does nothing to lubricate your engine, so the more actual oil it displaces the less lubrication you get. Worse, the chemical itself breaks down under heat and stress and causes harmful engine deposits. You can find a very wide "viscosity range" in a synthetic oil with relatively little additive to make it work, where a similarly "wide range" in a conventional oil would be chock full of that stuff. Not good.
Anyway, here is a link to the AAA's results:
http://newsroom.aaa.com/download/10250/
-mickey
Personally, I won't put conventional oil in my lawnmower.
The only application that I now of where synthetic oil is specifically DISAPPROVED is in piston general aviation aircraft engines. Companies like Lycoming and Continental forbid the use of synthetic oil, though semi-synthetics are approved in some applications. Why? I've been trying to find out for years, and the closest I've come to a definitive answer is that synthetic oil doesn't get along with the high levels of tetraethyl lead that's still found in aviation fuel. (Though I find the explanation a bit weak.) Personally, I lean toward the theory that pilots are just extremely conservative.
One of the benefits of synthetic oil that's often overlooked is that it has much better viscosity stability across a wide temperature range than conventional oil, and thus needs considerably less Viscosity Index Improver. For example, a 5w30 synthetic doesn't need nearly as much of that chemical additive as a 5w30 conventional. The Index Improver chemical does nothing to lubricate your engine, so the more actual oil it displaces the less lubrication you get. Worse, the chemical itself breaks down under heat and stress and causes harmful engine deposits. You can find a very wide "viscosity range" in a synthetic oil with relatively little additive to make it work, where a similarly "wide range" in a conventional oil would be chock full of that stuff. Not good.
Anyway, here is a link to the AAA's results:
http://newsroom.aaa.com/download/10250/
-mickey