I just went out and bought nearly 4 cases to start using in my '97 Ranger,'03 Ranger,and '94 Corolla.The Corolla has 187000,'97 Ranger has 33000,and the'03 has 9400 and all of them have been changed 3 to 5000 miles religiously.Some of the posts I have read scares me"concerning oil leaks" PLEASE...