nickmckinney

ZDDP attaches to the metal like a buffer, so its only needed when there is metal to metal contact. Street RPM range with the pan always full you don't need as much, higher RPM and/or pan starts sucking dry you need as much as possible. Tighter clearances are mostly BS on these motors, they have the same clearances as a late 90's 5.0 engine. Only motor run looser usually is an aluminum block 4.6 when its cold, when it gets hot it gets the same clearances as the iron.

BTW - we are doing some testing of an aftermarket part that we hope will help the cam bore scoring problem these motors have, 30W oil gives 15PSI at idle in a typical 4.6, guess what the pressure in the head is after the factory restrictor? A whopping 4-5PSI.

Only difference between a 5W30 a 10W30 and a straight 30W is the amount of viscosity modifer blended into the oil to make it less viscous when cold. The viscosity modifer does no other help. Pure synthetic versions of the same weight need less modifer. Anything you add to oil changes the ratio of the oil and additives, race oils get more antiwear and friction modifiers, and diesel spec get both the extra antiwear and more detergents.

Basically if street driving primarily use whatever oil you want, there isn't any significant difference anymore. If you want the inside to always sparkle clean and want more protection use a diesel spec. Many fleet programs do this very thing as typical fleet 15W40 is a diesel spec, and to be honest that is where I find my most pristine engine cores. 400,000 4.6 motors run on 15W40 their entire life and the insides look and measure like new. Only thing bad are the valve seals as this point so the intake port is the only dirty part of the motor.

lizzyfan

I use Motorcraft blend, good stuff!
I also add Trick Flow engine break in oil as it gives you Phosphorous/Zinc that most oils are lacking these days

FlamingoGT

The only thing that I have heard that I even deem as worth thinking about being credible is when going between dino and synth to stick with the same brand and class. And if you think about it, that is what a semi-synth oil is.
I personally have always run Mobil1 5W20 and have no intentions of switching. If I was going to run something else, it would prolly be Motorcraft. But just about any name brand oil of a current spec should be fine.

ShadowDrake

Motorcraft is actually a great oil - it has a relatively high ZDDP count, compared to others. That's more important than brand. ZDDP additives are no problem either. With the price point of the stuff too, you really can't go wrong.

Motorcraft oil all the way.

Frostbitten

motorcraft sells fully synthetic oil now too

smashten

i have recently been switching fluids over to amsoil. I heard about running a cleaner when switching from conventional to synthetic after I switched. The synthetic cleaned the engine on my tundra. I was suprised at the carbon that came out of a 50,000 mile engine that had frequent changes. Not sure i would want that plugging up the passages on my gt engine. already had timing chain tensioners and lash adjusters fail from a sludged engine.