Just found this regarding JP-8 smoke production.
The lack of adequate smoke with JP-8 in the Vehicle Engine Exhaust Smoke System (VEESS) is detrimental to the effective use of JP-8 as the single battlefield fuel. The VEESS is considered a force multiplier and is very critical in armor strategies. Adaptation of an auxiliary tank containing a POL product that provides adequate smoke is a possible solution.
http://en.scientificcommons.org/18866476
I think they tried to combine the JP-8 with 5% crankcase oil at the injection port.