I'm going to change the S60 to Synthetic oil and will be changing to Amsoil 10W-30 because I have heard only great things about it. My question is for the first oil change, switching from Dino oil to Synthetic. I have heard that the first time after you switch you need to get a oil change in 1000 miles. Then I talked to a local shop that carries Amsoil and they said that they can run and engine flush to get rid of the old oil. Which way is the correct way to do it? Any other recommendations for changing like a different weight oil? I like in Sunny Southern California if that helps any. TIA everyone!