Some of you may or may not know me. I'm the forum engine lubrication guru. We have a big used oil analysis thread in the GT500 section, one UOA there is related to this section, so I thought I would share.
UOA Post
UOA Post
I just got my 15w40 oil analysis back for my Motorcraft oil. I can't wait until the next one as I switched to Valvoline Extreme Premium Super Blue 5w40 (I think that's what its called) and its quieted my motor down significantly.
Amsoil is junk. Texas oil.
I've had a million valve covers off and every single time i can tell they use Amsoil or a like products.
Tony@lrs try running motorcraft cj4 10w30
Im a 10 year certified power stroke diesel technician. I work on them daily. I also own one. 2004 6.0.
Been running 15w40 Royal Purple since the first oil change in the SVTP F-350. They told me that their 5w40 HPS has a diesel add pack in it and is more robust than the regular 15w40 I've been running.