Green’s Dictionary of Slang

antifreeze n.

[ext. of SE use, i.e. both refer to their supposed prophylactic powers against cold]

1. alcohol, esp. cheap and as drunk by tramps and alcoholics.

[US]Kramer & Karr Teen-Age Gangs 185: Take this ten and stir up some booze. Maybe can’t get anything good so late, but don’t bring any more of that antifreeze you got last week.
F. Bonham Durango St 161: We just took a little antifreeze to loosen up our engines [HDAS].
[US]M. Cherry On High Steel 81: Timmy, despite a body full of antifreeze, complained without pause.
[Can](con. 1920s) O.D. Brooks Legs 111: We saw a rubby passed out in a doorway [...] ‘He’s so full of anti-freeze he wouldn’t ice up at the North Pole.’.

2. (drugs) heroin.

[US]Wentworth & Flexner DAS.
[US]ONDCP Street Terms 2: Antifreeze — Heroin.
[US]Eble Campus Sl. Apr.