The Mallory is not up to the task of pumping WVO - especially cold oil.

The only decent option is the FASS HPFP, but even it is known to have a relatively limited lifespan in VO service (mine have run 40-60k miles). FASS will rebuild them for about $125 (usually ) when the motors finally burn up.

Hopefully, BFT/Vegistroke - forum sponsor here (previously DFA) - will make a stand-alone version of their superior-to-FASS Scorpion Pump soon... (it is USER rebuildable! )
Pumps and Parts - Biofuels Technologies