In my GT I'm using 0w-20 and an Amsoil filter. I'm sticking with a 5k change interval even though just about every time I start it up it gets to run for a bit of awhile. I'm sticking with "20" because I think we are resonably sure the Ford engineers are nimrods.

Theory is that 85% of your wear is at start up. I'm thinking less with Amsoil. Theory is that when you start up the cold running engine puts contamints in your oil. It takes 20 minutes of run time before these contaminats start getting burned off. This is related to what oil companies call "Severe Service" recomending more frequent oil changes. I've definitely found that to be true on an automatic transmission.

My PU with the aforementioned automatic transmission now uses Amsoil and Amsoil filter with an approximate 8k oil change. For 18 years and some 160k miles it was synthetic oil every 4k miles. Went to 8k because currently 98% of the time it gets started, runs about 25 miles of mostly highway and gets shut down. Probably nearly the best engine oil type useage.

 

I think the reason Ford adamantly recommends 0w-20 is because some 30w oils have more viscosity than the cam phasers like. Synthetic oil has less viscosity/flows better and I think we can get away with using 30w w/o problems.

And I stick with 0w-30 due to startup protection, like you said.

 

0W-20 Amsoil w/ Amsoil filter at 8-10k mile change frequency, only because I currently have money to burn. Otherwise, I'd be absolutely happy with Mobil1 5W-20 and any decent filter (M1 or Motorcraft) at the same change frequency in the Stang. I've been using Mobil1 in other vehicles at 10,000 mile changes and all 4 of those have gone beyond 200,000 miles w/no issues whatsoever plus my current SUV at 151,000 + miles.

 

How many miles a year do you drive Nuke?

 

~20,000/year on the Stang (NOT my DD but is my long distance runner)
~15-20,000/year on my SUV (my DD and tow vehicle)

 

I've been using Amsoil for three or four yrs now in everything I've had during that time, never a problem.

Has anyone had their oil tested through Amsoil? I get my oil off a friend of a friend and he's been trying to get me to test it before changing it. I change the car and truck once a year (new filter every 3 months), I call him up with an order and he always says you don't need oil you need it tested. If the test comes back clean he doesn't make a dime on selling new oil. The amsoil thing is mostly his fun money job so there's never any pressure. He says he's got commercial vehicles and cop cars going well beyond the scheduled changes with no issues.

 

I have been using it and selling it for the last 12 years. Ive tried most of what they sell, and sold what all of what they sell. The only complaint, well 2 complaints, is that it cant be bought "just anywhere", and the price is more than what most people consider acceptable for oil. So you spend $60 every oil change. Whether its 3mo, 6mo, or 12mo (or more), its still cheap protection. The last walk-in to buy some said he was going to get it tested out of his new Malibu. When he comes back by, I intend to ask him if I can make a copy of his results.
I have quite a few people that come and get for themselves, or have me change it for them. They all love it.