Does it have to be in the oil like they did with cash for clunkers ?
proven by the mythbusters, will effe a car better than anything elsebleach- oxidizer
i worked in a grinding shop for years and had access to all kinds of steel and alum grinding swarf. I tried this and nothing ever happened. I was told you need to mix and oxidizer into it.50/50 mix of rust and aluminium filings, mix in to a paste with a small bit of flour & water, apply in a square on the hood of the car, ignite with a strip of magnesium or a blow torch and patience
get the hell out of there because you do not want to be around when the owner finds the engine burned of it's blocks or if the fuel line ignites . . . especially if the fuel line ignites
tho that might go a small step beyond minor vandalism . . . just a tad