Thanks guys for the info. I need to change the oil in my car and was going to use the standard 20-50 I been using with Lucas ZDDP additive to it. I was told that since it is a detergent oil and adding the additive would cancel it out or not work that well. That is why was asking. I do push the car hard on the street so I do not want any issues. I was figuring Brad Penn or the Joe Gibbs oil or the diesel style oils. Figure diesels get worked hard but I know they changed the formula on those too and do not rev like the cars do. Still not ready to make the plunge into synthetics. I like Dinosaur oils but I know oils have come a long ways. Now the oil I just looked at picking up for my truck says Conventional/synthetic blend on it. Just seems odd to add the two together.