I just purchased a new 09 duramax and have some questions. I have only owned chevys before but they had the 6.0 gas in them. I pull a 36' fifth wheeel toy hauler and am looking for any info you can give me about anything. I have been around duramax's before and drove them but never had to learn about them. Some of my questions are changing the air filter to a k&n, whether or not to switch to synthetics, running additives, or any other advice you would have for me. Thank you looking forward to getting all the info I can