2004 Arc Convert. almost $100 for synthetic change at dealer with lots of warantee item, they werent happy, real bad experience. I looked at dipstick oil it was DARK brown, drain plug and filter cap looked as tho it has never been touched. It has been driven about 3-400 miles and has rained in past 3 weeks since i picked it up. Is it possible to look like that and is there any way to prove it?