How to connect pipes of different sizes?

[IIA]

I'm re-installing the PCV system in my truck and I've realized that the small fitting that sticks out of the bottom of my oil filler pipe is a different size than the pipe I need to connect it to. It looks like one is 1/4" and the other is 3/8". Would it work to just use a piece of 3/8" rubber fuel line as an adapter and tighten the hose clamp down on the 1/4" end?

[jimrr]

1/4" seems small but i see no problem with your plan, it's just a slight vacuum wanted on that line is all. (and the oil fumes) , you'll want to clean it out once in a while depending on engine blow by)