Rough idle at a stop light,sign. 25000 mile. 3000 miles after last oil change was a quart low. normally i do my own oil changes but i bought the truck with 16500 miles on it and got a couple free oil changes when i bought it. no oil drips, i always park in the same spots at work and home. gonna start changing my own oil again and gonna go with mobile one 5w30. all my other cars and trucks have had synthetic oil so i figure gotta change this one over too. any guess about the rought idle? or if synthetic is not a good idea? Just would like help or ideads. thanks.