Ken,

I'm sure orange is OK for a coolant application, but the DD original equipment hose material is the blue, and I think Jerry is right as to the source. And that stuff does seem to last forever.

I have orange for the joints for the pipes to the intercooler, but that is a series 60 and it has an air to air intercooler. (Your 8V92 has a coolant to air intercooler that is internal on your engine) I know Prevost used a very expensive high quality orange hose that was designed for fuel, and that material was used for the hose to the filler neck and between the main and auxiliary tank.

At the POG rally I'll show you mine if you will show me yours.