The only weakness of all-conventional oils are temperature extremes, both heat and cold. Conventional oils contain a hodgepodge of different lengths of hydrocarbon chains. At extremely high temperatures the shorter hydrocarbon chains can break-down and evaporate, reducing the lubricating effectiveness of the oil. At extremely cold temperatures the longer chains will cause the oil's viscosity to increase. Viscosity is basically the measure of a liquid's resistance to flow. Therefore, as viscosity increases lubricating, effectiveness decreases.
The uniformity of the length of hydrocarbon chains is more closely controlled in synthetic oils, thus their behavior at given temperatures can be more precisely predicted.
All that being said, a two-year engine-oil study conducted by Consumer reports showed no significant difference between conventional and synthetic oil in 75 New York taxi cabs.
1997 ZJ 5.2, IRO 4.5 - Clayton LA's, 33x12.50 KM2's, 15x10 Soft 8's, NP231 w/ SYE, Rubicon D44's F/R - Air Locker - BTF Diff Cover, CAI, IRO 3" Cat Back
Last edited by acarnes83; 10-25-2009 at 08:04 PM.