The oils for our trucks (CI-4 Plus) will perform at the drain intervals recommended with out a problem. They can handle the soot. The testing is done with much higher levels of soot than we will see in a typical oil change.
Now the question really is Synthetic versus Dino?
In order to gain the benefits of fuel economy you must reduce the viscosity of the oil to a 5W-40 or 5W30. Amsoil does not have a licensed product for this(see below).
A PAO sythetic molecule is great at high temp. However, We can make the Group III perform at these levels. These are the Oils Wayne talks bad about. We can do this at a cost to you the consumer at whole lot less and still get the extended drains.
I am no longer working for a particluar brand; In fact, I do not work in the industry at all. I did spend over 20 years in the selling oil to the HD industry.
I would not buy Amsoil because of the cost. It is way over priced for what you get.
We all spend way to much money on our trucks making mods. Save the money on by-pass filters and use a good quality oil and be done with it. Don't waste your money on a 15W40 synthetic
I use a product made by CITGO. It is called SynDurance 5W40. It is made with 40% PAO and 60% Group III. It is a full synthetic that will meet the new specs when released in September. It cost around $15 for a gallon. I change it every 10,000 miles because it is cheap. They do offer free oil analysis when you buy it. My test results say I can keep going! CITGO has customers going over 90,000 on an oil change.
Mobil and Shell make great products as well. Never been a fan of Chevron but the new Delo 400 is a good product.
It is expensive to license a product with API. AMSOIL makes a whole lot of money, you would think they could afford to have all of their products licensed.
http://eolcs.api.org/DisplayLicenseInfo.asp?LicenseNo=0995
License No Company Name
0995 AMSOIL INC
Brand Name SAE Viscosity Grade Service Category Current Expiration Date
PCO 15W-40 CI-4/SL** August 8, 2006
XL 10W-30 SM/CF* August 8, 2006
XL 10W-40 SM/CF August 8, 2006
XL 5W-20 SM/CF* August 8, 2006
XL 5W-30 SM/CF* August 8, 2006
* Energy Conserving
** CI-4 PLUS