I have decided that I would like to switch to synthetic oil in my 2009 ford focus. It has 35,000 miles on it and I was wondering what would be the best oil to run in it for my driving conditions. I drive 10-15 miles each way to school 3 times a week all together I drive about 200 miles a week all being short trips under 40 miles each way. When I drive home from school I drive 550 miles straight half down 55mph highways and half down 70mph highways. I also live in a climate that gets very cold winters. I have mods on my car and intend to keep getting power out of it so I want to have the best protection I can get. I do get into it every once in awhile but only when its warm but I am typically a pretty economical driver. What ever oil I end up using I plan on using pureone puralator filters. What are your recommendations for what type of oil best suits my driving and how long my oil change intervals should be.