Umm ... diesel ... that's a good question ... we have a gasser.
I don't think I can help you much with that, nothing comes to mind of the Flying J variety along the way.
If you do decide to make the Aurora loop when you come off of I70 to 270 you will make good time unless you are after about 2 or 3 pm, it gets pretty slow but usually does keep moving. And it will be slow when it joins I-25, but will loosen up shortly thereafter.
The only thing that comes to mind ... and I can't remember how open it is for pumps, etc. ... is Johnson Corner up north of Denver. It's exit 254, Johnstown Exit. If nothing else you could have one of their Cinnamon rolls! ;D
I know there are stations up north just off the highway but haven't paid much attention ... too close to home I guess.
Here is the web site ...
<http://www.johnsonscorner.com/index.html>
If I think of anything else I'll let you know.
Howard