I don't question the quality of the product, I've used it myself and never had a problem. I only question if it's the best choice for a MDS engine where viscosity seems to be so important AND where the truck owner is intending on leaving it in for a very extended period of time because of the cost of the product.
I NEVER go more than 6k without changing, and that's just a recent thing since I started using Royal Purple. Used to be 3k with Mobil 1. Assuming 6k changes max, I'd have no problem running Amsoil in an MDS truck...

 

I ended up buying the Amsoil 0w-20. According to Amsoil, it is supposed to replace the 5w-20, which they offer as well. I also bought the Amsoil filter, and the Amsoil engine flush. My friend is a "preferred customer", so it cost me about $81 for the 7 quarts of oil, filter, and engine flush. I'm kind of anxious to use the 0w-20. On my 360 motor, Amsoil did not offer the 0 weight oil for the motor. Like most of you, I as well run my synthetic oils for 5k miles. To me, I think it defeats the purpose of buying synthetic oil if your going to be waiting 15K-25K to change it. I don't buy synthetic oils for longevity of intervals, I buy it for the quality of the product for my engine. I can't wait to get the conventional oil out of my truck and begin tracking my own oil changes with the truck, just love that kind of stuff. When I used the engine flush on my '01 when I did the Amsoil switch over, it was really fun watching all of the white smoke coming out of the tailpipes.

On a side note, I wanted to get your guys' two cents. It says in my manual that both differentials should have fluid changes at 30K miles. I have 28,500 miles at the moment. I was planning on using Amsoil. I did my differentials on my '01 with no problems, will it be as straight forward on my '05 Ram?? Any tips for doing the job?

 

That is a pretty old test, I would guess that a few things have changed since then. Amsoil FTW

 

I doubt it. But the fact that it does thicken is clearly indicators of additives that I'm sure they aren't going to wanna change for obvious reasons.
I would have no problems running Amsoil. I plan on doing 5kmi Synthetic change intervals anyways so, Mobil1 vs Amsoil...Mobil 1 is at the local store. Amsoil is not. That is the Only reason I myself run Mobil 1.
There's gives and takes from one company to the next, I doun't think it matter either way which oil is used. hell, manufacturers are giving 100kmi warranties and not requiring the use of Synthetic! Most of it's a gamble on length of ownership, but it's also their trust in the durability of even the dino oil these days.

Oil changes back in the 60's and 70's was like once a year or when ever you could afford it. Changing oil like your underwear is a complete waste. Run dino oil for 3kmi of street 5kmi of highway and Synthetic 5kmi street/towing or 7500highway(any longer and you'd want to change the filter and top off)