FORDGUY60435

Who ever told you this is off their rocker. Use a high quality 5w20 oil and nothing but the motorcraft FL820S filter.

bryan lukehart

I don't thank 5-20 is worth a crap my truck was running really bad knocking at low rpms I put motor craft 15-40 in and my truck has never ran better I have a 07 f150

Flareside302

This engine builder is doing the typical 70's though "thicker is better".

It's not. Especially NOT on a modular. 0w20, 5w20, 0w30 or 5w30, or 10w30 only.. 10w30 is ONLY IN serious hp builds.

4.6/5.4's don't have cam bearings. They ride te head on oil as the bearing.. To thick of oil and it can't get between head and cam. You'll eat up cams and head surfaces.

Thicker oil pressure raises oil pressure which means the pump is having to work harder. much Harder. With a quality oil, it'll have plenty of film strength to not fall off surfaces. Used to use the thicker oils to cling to stuff cause he film strengths were poor