I've been considering trying out Amsoil for a few things. I noticed that they have a coolant that is rated CAT EC-1. Does this make it compatible with Zerex, CAT, Rotella, etc. or atleast a viable alternative to them? Its a Propylene Glycol product. Here's the link.


AMSOIL Low Toxicity Antifreeze and Engine Coolant

 

Simple answer is that the EC-1 rating means it meets high standards for corrosion protection, heat transfer, cavitation resistance and most significantly to us 6.0 owners, it contains no silicates. Compatibility with other brands of EC-1 coolants isn't assured as the other additives used to meet the standard may be different. I'd recommend picking a brand and using it exclusively (don't mix with other brands). I'm sure the Amsoil coolant would be a fine choice.

 

Here's another place to get lost reading in -- actually there are experts over there on a ton of things, but my link is direct to the coolant forum (enjoy...):

Cooling System Fluids & Additives | Bob Is The Oil Guy