[VAC] Antifreeze vs Drains

[Gary Quamen <gquamen@xxxxxxxx>]

Hi all:

Item no. 7 in the owner's manual instructions for winterizing my '67 
Safari says, "Pour about a cup of kerosene into the lavatory, sink, and 
tub drains to prevent freezing of water in the traps; DO NOT USE 
ANTIFREEZE".

So, last winter I dutifully poured kerosene in my drains.  It really 
smelled bad.

This winter I poured about a cup of the ol' RV Pink, propylene glycol as 
I recall, in my drains.

The question:  Does anyone know why the manual would specifically outlaw 
the use of antifreeze?  Effect on ABS pipe?  Ethylene glycol?  Other?

Thanks,

GQ '67 Safari