no your warranty cant be voided. if you are really worried keep all receipts of maintenence parts. make a username on mysubaru.com. you can log in and keep track of all oil changes etc. as far as mobil 1 alot of people on nasioc dont seem to like it and say our cars consume it more than other oils. i personally use castrol syntec 5w30. as far a synthetic, subaru came out with a bulletin that states 2011 and newer turbo cars are required to use synthetic oil. previous years are recomended to use it. i would also use subaru oem oil filters. they have the proper psi bypass valve for cold starts. i hope this helps.