I poured it in the gas tank (and I still do it at least once a month), I poured it in the oil crankshaft (1-2 days before I change my oil), and I poured some in my brake booster line with the engine running (once every 4 months or so). I usually do that [brake booster] at night in a secluded area so that I can remain anonymous.....
..... just kidding, it gets really smokey once it starts going through your system and so it helps to be out in the open in a secluded lot.