Abstract: This disclosure pertains to pumping of heavy petroleum products such as crude oil from 8API gravity and greater. A tubing is packed off by a production packer in a well casing and a piston is reciprocated in the tubing below the packer by a pumping rod to pump oil upwardly in the tubing. Above the packer is a standing valve which places the interior of the tubing into fluid communication with the annulus between the casing and the tubing on an upstroke of the piston and closes the communication path on a downstroke of the piston. Above the standing valve is a packing means through which the pumping rod extends, the packing means isolating the interior of the tubing above the packing means from the standing valve below the packing means. The tubing above the packing means is filled with a light weight fluid. Reciprocation of the rod is principally through the lighter weight fluid and the weight of the lifted oil in the annulus is isolated by the standing valve from the tubing below the packing means.