1997 Mercury Mountaineer -I started my truck yesterday and heard a squeal-pop-hiss. Kind of a burnt smell that dissipated quickly. My truck sputtered a bit and then continued to run normally. It sputtered one or two more times before I got it home, about 10 miles away.Now, when I start it...

I recently bought a '97 Mountaineer AWD. It has 185k mi. It's in great running condition.I have no idea when the last oil change was. When I check the dipstick the oil that is in there now is blacker than Wesley Snipes and is a little bit grainy.My question: Should I just change the oil and...