i recently did an oil change on my 03gs300 and im sure guy i bought the car from was using synthetic..So im at the store buying oil somehow i buy regular 5w30 oil and i dont even relize until doing the oil change....so now should i change it again and use synthetic or is it ok for now and drive it for 3000 miles or less cause i feel like changing back rite now would be bad So wat do you guys think thanx...