I took my 07 F150 in for service and they replaced the cam phasers and did an oil change on the truck,which I did not want them to do, but they used the Motorcraft 5W20 semi synthetic. I have only owed my truck for a year now but have always put Mobil 1 full synthetic 5W20. I asked the service manager if using the semi instead of the full synthetic would be causing the ticking noise. His response was that the semi synthetic was a thicker oil the the full synthetic,and when the oil gets hot it would not thin down like the full synthetic would. This sounds like total BS to me,but is there any truth to this?

 

No truth to what he said, he does not understand oil and should not have opened his mouth. But being that we are on the subject I find MC 5w20 to be superior to the Mobil 1 you were using and there is plenty of independent tests and UOA's and VOA's to back it up. Mobil 1 for the price is about 3.00 a quart overpriced.The cam phasers can be tricky in these trucks its why most recommend not veering away from the oem filter with the silicone ADBV in it as it has proven to be reliable in these engines and was designed to combat the cold start/dry start oiling issues.

 

Very educational reading... All you ever wanted to know about automotive oils.

http://www.bobistheoilguy.com/cms/index.php?option=com_content&view=article&id=83