"Ford has spend millions to dollars to determine the right oil for their engines inclucing the 4.6 V8 which also uses 5W-20. What puzzles me is people come here asking what is best and we usually tell them follow Fords owner manual and adhere to the maintenance schedule. Then our moderator comes along and says Ford knows from didley squat, use motor molasses 15W-40 oil. Don't you run a state highway dept garage or something?"
Hey Huney1. I never said not to use what is recommended from the manufacturer. If I did, please show me where I said anything that says the engineers at a manufacturer does not know any thing. I simply stated we use 15w40 in our fleet of vehicles. In all my personal vehicles, I use what is recommended by the manufacturer. We are a government fleet and purchase oil in bulk quantities and we get lower price on the 15w40 than any other grade. So due to the powers that be, we use the cheapest bid product. We also may not have all the troubles the outside agencies because we do change our oil on a very regular basis. It also differs from the manufacturer's guidelines. But it works for us. I did not mean to ruffle your feathers, but there is always more than one side to the story. You can search the internet and other places and see all the tests that each manufacturer does and their brand is always the best. It is like being in a class on theory. Somethime the theory works in the real world, and sometimes you have to bend the line a little to make tha theory work.
And yes Huney1, I run a local Police and general government fleet and have been in automotive repair for over 50 years total. So there is a lot I have seen, tested, used, proved, and disproved various products over that time. So as I stated earlier, please show me where I have said to ignore manufacturers specifications on any product they use or install on their products. Keep web searching and I will keep grease under my nails. Good comparing notes with you again though.