My heater core was just replaced, and it leaked into my car under the floor mats and carpet on the passenger side. It's oily and slightly brownish which is not what I would expect from antifreeze.

I have a wetvac, so I figure I should shampoo the carpet. Any shampoos or chemicals that I should try?

I was thinking of lifting the carpet and cleaning the floorboards first. Then I was going lay some plastic down be/w the carpet and the floorboards and shampoo the carpet. Next vacuum it as dry as I can.

 

If you remove the 2 front seat screws and loosen the rear ones a little you can remove the carpet assembly and wash it with a hose then let it dry.
The hardest part is removing the foot rest pad. You have to lift the bottom I believe and slide it up or down to get it out. I always forget which way it is and try both till it comes out.