Chugger pump impeller isn't SS?!

Just got a couple replacement heads for my march pumps -- the SS chugger heads. I'm pretty annoyed that they impeller is plastic...

On another note, I'm looking at my March pump and it says:

"For longer and quieter performance keep housing filled with liquid." Is it politely telling me not to run it dry, or is it suggesting that I keep the whole thing submerged in a liquid like an oil?

 

Don't run it dry. Or submerged in oil...

Cheers!

 

Oil would probably increase resistance against the motor...

That said, I have seen people run computers submerged in oil as a means of cooling them. This technique doesn't involve any mechanical parts, though.

 

Just got a couple replacement heads for my march pumps -- the SS chugger heads. I'm pretty annoyed that they impeller is plastic... Impellers can't be made of SS, it's too heavy and would decouple the magnets.

On another note, I'm looking at my March pump and it says:

"For longer and quieter performance keep housing filled with liquid." Is it politely telling me not to run it dry, or is it suggesting that I keep the whole thing submerged in a liquid like an oil? Just don't run it dry.