Yeah, the distributors add something to the propane to give it that distinctive smell. I think it's an oil. In any case, it has a bad effect on some regulators depending on the material of the resilient seat over the internal aperture. The oil causes the material to swell which really throws off the calibration. Is there an adjustment screw that would allow you to recalibrate the pressure? It might be cleanable depending on how it's built - most of the cheap regulators are swaged together and any disassembly tends to be destructive. If yours is built with threaded fasteners, cleaning it and/or replacement of the resilient seat should be possible.