Just took my 2007 Expedition into my mechanice for a loud rattle coming from the front of the motor at every start up, a surging that to me feels like a misfire, and a lack of power. All have been getting worse. He told me it was 6 quarts low on oil. This car has hydraulic lifters, hydraulic cam, and hydraulic timing. Its always had oil pressure and no check engine lights. Ive even tried to pull history codes(Snap On scanner) and nothing. Being that low on oil the lifters should collapse and not open the valves timing would be screwed and the car shouldnt run at all. Someone please tell me if Im correct and being fed some BS.
The only thing I can think of is that the last guy to change my oil didnt put oil in the car. There are no signs of leaking and the truck doesnt smoke at all.
The rattle on start up is the timing chain tensioners rattling from the gaskets being blown. You need to replace the tensioner gasket and arms. This is not from being low on oil. It is fairly common on the 5.4l motors and happened to mine at 50K and I change/check my oil regularly.
This was covered under my 5/60 power train warranty.