Visflo
Visflo is the lane conditioner that AMF Belleview Lanes uses to maintain their bowling lanes. This product is manufactured by AMF, so it's their own brand. All AMF bowling alleys use this product.
On Reddit, someone pointed out that Visflo isn't flammable. This discussion had a lot of people convinced that this meant Eric and Dylan had no idea what they were doing when choosing to include Visflo in their BLEVE setups. How could they not know Visflo was useless to their plan? Why would they use something that wouldn't even ignite? They must have been stupid.
Not so fast.
While it's true that Visflo isn't flammable, that's only a technical definition related to its flashpoint. Because of its flashpoint, Visflo is considered combustible. Both flammable and combustible liquids can catch fire.
A liquid can be considered "not flammable" and can still catch fire easily (like Visflo does). Flammable doesn't mean "something that can catch fire" and therefore, something that isn't flammable can't catch fire. Quite the opposite. Visflo is mineral oil. Mineral oil is a petroleum distillate. It can catch fire easily.
Flammable v. combustible
Flammable liquids ignite easily, while combustible liquids need more heat. Both can ignite.
A flammable liquid is defined by NFPA as a liquid whose flash point does not exceed 100°F (37.8°C), when tested by closed‐cup test methods, while a combustible liquid is one whose flash point is 100°F (37.8°C) or higher, also when tested by closed‐cup methods.
However, OSHA defines a flammable liquid as any liquid having a flashpoint at or below 199.4°F (93°C), and these liquids are further classified into four categories. Please keep in mind that these are the NFPA and OSHA classifications. Other regulatory schemes define these materials in different ways, so it is important to consider how the material is being used (and therefore which regulation applies) when managing flammable and combustible materials.
The flashpoint of mineral oil is about 335°F, which makes it non-flammable by both NFPA and OSHA standards. But, it doesn't matter because it's a low-heat combustible; if you so much as drop a lit match on mineral oil, it will catch fire. It can be ignited extremely easily with fire. It can also cause an explosion easily. Combined with gasoline, it's even worse.
So they not only knew the correct "recipe" to create more intense fires... they chose (and had access to) the perfect ingredients. If they merely "guessed" and hoped for the best, that would be one hell of a lucky guess.
They likely had plenty of experience starting fires with Visflo before the shooting. Being easy to ignite and virtually odorless, Visflo would have been the ideal choice for experimentation compared to gasoline, which would have given off too much of an odor for them to go undetected.
They knew exactly what they were doing. And they weren't the only ones in their group with this knowledge and experience.
Here's a screen shot from the Visflo MSDS sheet for the product they used:
