What kind of oil should you use in a 1995 Mazda Millenia SE?

the standard 2.5 motor can use 5w30 during the winter and 5w30 or 10w30 during the summer. however if you have high mileage and have not changed the valve cover gasket and spark plug grommets use thicker oil to keep from fouling the plugs because those gasket wear faster than usual.