You can get clean oil from any transmission shop, repair shop, hydraulic shop most of the time if you give them a 55 gallon drum and ask them to fill it and then pickup it up right away and leave another one you will be good. Also you can find used and rebuilt heaters on line. The biggest problem we have with ours is because it runs 24/7 at 70-75 degrees all the time it has to be cleaned out once a season ( I just did it last week) and the oil filters need to be cleaned at the same time.
