If you cut the WMO or WVO with RUG, it should thin it out enough that you don't need to pre-heat it. You will want about 15% RUG to thin it out close to the viscosity of D2. Be very careful mixing WMO and WVO. The particulate in the WMO will fall out and leave a nasty sludge that will clog filters unless you have a way to drain off the sludge before using the fuel.

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1991 F250 super-cab 7.3 IDI. (rebuilt by me) Banks Sidewinder turbo, hydroboost brakes, new IP and injectors.
2003 S430 - 107K
1983 300SD - Tanoshii - mostly restored ~400K+.
1983 300SD - Good interior. Engine finally tamed ~250K.
Monark Nozzle Install Video - http://tinyurl.com/ptd2tge