I think you are wise to wonder exactly that.

 

Cool, thanks!

Within the next couple of weeks I am going to send in a virgin Motorcraft oil sample to Blackstone to get a baseline reading, along with a sample of the oil after 1500 miles. I doubt the oil's properties will have changed much in that short of time, but I would like to see what metal and casting material was thrown off from the factory engine build.

 

Amsoil does not make a 5W50 oil. When you go to their website & enter either the BOSS or GT500 engine, the results are: no recommended Amsoil product.

I like Amsoil & use it in my dirtbikes. I also use Redline products like their water wetter. Since our GT500 is only street-driven, I will feel confident using either the Motorcraft or Mobile1 full synth.

Why, because my dad told me so. Why should I believe him? He was a Petroleum Engineer & the son of an auto mechanic. His entire career was working on refining catalysts for petroleum. And, a number of patents for the current refining process for petroleum have his name on them.

 

Whatever you decide to go with at least use what Ford recommends. Like someone said earlier in the thread, Ford didn't arbitrarily choose 5w50 because they were having a weird day. They must have chosen it for a reason and if you stay with that then you won't have any warranty issues. That being said, I would rather use something other then Motorcraft, just don't see paying 10 a quart for an oil that could be manufactured by Mobil1 for all I know.

 

I've used amsoil in a couple of my last cars, it came out right after i put it in. Last car was 2005 GTO, did motor, trans and rear. Motor noisy, trans notchy and rearend noise.

I used Shell Rotella for the GTO and i'm sticking with the Ford oil for the Mustang.

 

fun Pennzoil (new synthetic motor oil out of natural gas to consider) promo video clip for viewing...

 

Pennzoil 2.0 promo clip: Demon gets Exorcised...

 

OEM oil. I get it cheap from the dealer and I keeps the warranty.