Abstract: Dewaxing control apparatus is adapted for use in a well casing containing a production tubing string defining an annulus within the well casing and a down hole pump which pumps oil upwardly through the production tubing. The apparatus has a housing adapted to be installed in-line with the production tubing. A passage in the housing places the annulus in communication with the interior of the production tubing for purposes of circulating a hot dewaxing oil. A cup packer positioned below the passage closes the annulus against downward liquid flows. A gas by-pass passage in the housing permits gases to be exhausted upwardly through the annulus during oil production despite the presence of the packer. A valve mechanism responsive to pressure developed by pumping hot dewaxing oil down the annulus closes the gas by-pass passage and opens the liquid transfer passage so that the dewaxing oil can flow into the production tubing and back up to the surface.