I'm pretty sure that a flow meter like the Ravens does not care what is being pushed thru it, molasses or gasoline, or anything in-between....it will measure the same gallon without any factoring. The "factor" you mention has to do with the pressure needed to force those liquids thru a hole, like a nozzle or a hose. So, even though it might take 2000000# of pressure to force that molasses thru the flow meter, the cal # should be approximately the same. Now, one's personal in-field gallon-pound-etc results could be different, so a slight amount of tweaking to the flow meter cal could be necessary. But again, I'm sure you normally don't have to re-calibrate for products. It is possible that the flow meter can get something caught on the vanes which could affect the initial calibration, but not very likely in my experience. That's a "here" thing.