I have a 2008 Mazdaspeed 3 turbo with the 2.3L MZR DISI engine....its about to roll over 10k miles and I plan to switch to synthetic...what would be my best bet? It seems like Pennzoil Platinum 5w-30 is the way to go...according to all the threads I've read...I know this is a safe bet but I wanted to get everybody's opinion before I jump in....I plan to buy my oil at wal mart in those 5qt jugs How about Mobil1 Truck and SUV? How about Valvoline Full synthetic? need some input please! especially for this 2.3L turbo!