Rice cooker question

Liz and I have two rice cookers of different sizes and we really like them. However, they have one problem in common that drives us crazy: some rice always sticks to the bottom of the aluminum cooking container and it is a pain to get it off. We have tried many things to keep this from happening like coating the bottom with olive or other oils and even greasing the bottom with Crisco-type grease all to no avail. Is there any trick to prevent rice from sticking or is it just the cost of having a rice cooker?

Good question, Jon. It's one I've been meaning to ask myself, as we have the same issue with our rice cooker.

The only one I owned (not using one these days) had a non-stick coating on the inside of the aluminum, so I erroneously figured they were all that way. No help here.