Hello everyone. I'm brand new here. I'm been trying to do a little research. I am an Amsoil dealer, but not a very good one. LOL I just got into it to get oil for my own racecars and sell to a few of my friends for their racecars. I would like to learn a little, because more and more people are coming to me with oil questions and concerns. One friend of mine has been asking me about oil for his Roush Mustang street car. It is more or less a toy that doesn't see regular drive time, and is only used in the Summer. He wants to know if Amsoil is worth his money. I'm honestly not sure. The car is new enough that it is still under warranty. The recommended oil is 5w20 with OCI of 7500 miles. I was surprised to see this is all the Amsoil 5w20 is recommend for. What is different about this weight than others? He isn't looking for an extended OCI, anyways, though. He wants the "best" oil, but doesn't want to waste his money. Specifically, he has asked me about Amsoil vs. Royal Purple vs. Motorcraft. He is currently using Royal Purple. What should I tell him? I want to be honest. He is also using Lucas oil stabilizer. From the little I have read, this doesn't seem to be a good idea. Am I right with this conclusion?