This is what I was told by one of the mechanics at 5 Corners Dodge. If you have always stuck with conventional than keep using it. As the motor gets older it has worn in using the viscosity and other properties of this oil. Synthetic, being more "slippery" thus making it easier to get pass worn seals and valves could actually produce a problem down the road. It's okay to protect your motor but you could be giving it too much of a good thing.