Looking for a good synthetic high mileage oil and filter for a 98 MB 320 6cyl that leaks oil. Something sold at wal mart which is close to the kids house that has the vehicle.. I told him Mobil 1 high mileage but i don't know what weights they sell im looking for something heavier than 10w30. He got this vehicle for free and wants to try to keep it running..(good luck) lol