Hello Forum. I read the following in my 2000 Ranger Owner's Guide, page 167: "Do not use supplemental engine oil additives, oil treatments, or engine treatments. They are unnecessary and could, under certain conditions, lead to engine damage which is not covered in your warranty." I will guess that most of you have heard of many products that are sold to be added to oil, some with religious fervor and testimonials from true believers in them. A late night radio talk show for truckers comes to mind. I have not put anything but oil into my oil. The only thing I have changed is by switching to 5W-30 Synthetic for high mileage vehicles (@ 154K in my case). No leaks, and for which I am thankful.So far, so good. Am I missing something in being more than merely suspicious of oil additives?