I'd recommend against using any inline lubricators. You're just going to
contaminate things, and a lot of tools which require lubrication are really
picky about what you lubricate them with, so it's better to deal with them
on a item by item basis.

I've got a simple filter/water trap (CH I believe) in my line.

Simple solution is to not put any lubricant into the filter. What is "CH"?

thanks

Ed