I have a sample of gear oil that I've decided I don't care to analyze. I need to take an engine oil sample. I would like to empty the gear oil, clean the bottle, and put the engine oil sample in to send it off. Is there anything wrong with this? How is the best way to clean the bottle so as to minimize/eliminate contamination? Just soapy water & a hair dryer? Or ether (well, starting fluid w/50% ether)? Or brake cleaner? Or something else? I could just go look for another bottle, but I'm not sure what kind of plastic it's made of or where to go looking. Thanks for all help and ideas.