When Synthetics first came out there was a big difference between them and Dino oil. The motors were very hard on oils, air filtration was awful and a 3000 mile change out was needed to get 100,000 miles out of an engine before needing a rebuild. These days there are very few Dino oils not up to the same specs as the synthetics and the current internal combustion motors are much, much easier on the oil than previous engines. If you research it you will find that Dino/Syn blends give you the best of both worlds. Dino oil has properties that are more beneficial than synthetics (film thickness at operating viscosity, polar attraction to ferrous metals, etc) and syns have better performance at high temperature. As I said earlier in this thread, it's the additive pack the oil company uses which really makes a difference in the performance/longevity of the oils. Spend $25 on an oil analysis from Blackstone Labs at the point you think the oil should be changed. The results will give you a measure of how much longer you have before you need to change it and how accurate the oil change monitor is.