The filter is on the passenger side of the engine. There is no belly pan to take off. You can reach it lying on the passenger side of the car - helps to turn the wheel, can't remember which way, but there's only two ways to try. Going back to conventional oil is fine. As someone said, check the manual. There's nothing wrong with synthetic oil, it's just isn't necessary. With conventional oil and regular oil changes the engine life will far exceed the rest of the car - this is either the good news or the bad news.