I have rattle (knack)noise from the roof when is closed. dealer said it is not fixable. is this true.? Also, what oil should I use when doing my own oil change.?

 

These IS convertibles seem to be prone to rattles. My 2010 had so many that Lexus bought the car back from the original owner under the lemon laws. But it was fixed by a dealer and put up for sale afterwards. So the dealer is full of it when saying it cannot be fixed. It is a case of the dealer not having a knowledgeable, competent technician. Take the car to another Lexus dealer, preferably one that sells more cars than the first one you tried.

As for the oil, use 10w30 weight as the owner's manual states. As for the brand, any of the name brands will be just fine. I personally like Valvoline, have been using it for many years. My only comment is that whatever brand you decide on, stick with it. Don't be using a different brand every time you change the oil.