Caltex isn't ****. They put "up to 5%" biodiesel in their fuel and I've used it, it isn't too bad.
You do need to get it from a high volume turnover outlet like a truck stop.
The ones to worry about are the Libertys, Uniteds, Metros and any others that sell "cheap" fuel. It's often up to 20% bio and there's no guarantee that "up to" means "no more than", it could easily mean "roughly, could even be 50%".
I'm not risking a $4,000 fuel pump, $1,600 in injectors and $200 in fuel filter just so I can save 2c or 3c per litre. Until biodiesel is much better, I'm sticking to dinosaur.
For what it's worth, Caltex is ranked 4th on my choice of fuel suppliers - in order Shell, BP, Mobil, Caltex then towing it.