Father has a 1998 toyota corolla. 1.8 liter, twin cam. It sems to have oil consupmtion issue.... my understanding is, this model engine is known for it. Would using some kinda additive, or high mileage oil slow it down? I change his oil every 3 months, usually has about 2,000 miles, but before this time, the oil seems to be down a quart and a quarter. Any suggestions? how about a 5w 40?