Drain skin tank?

[Morris]

Our boat is currently out of the water and we are going to be away for most of December. The coolant in the engine/skin tank is of unknown age/antifreeze protection quality and I am somewhat concerned about it freezing whilst we are away. Would it be best to test antifreeze (are testers reliable?) and if it seems OK from that leave as is, or drain down? 

[ditchcrawler]

Easiest and fastest, check antifreeze, Its more at risk out of the water than in.

Edited November 30, 2023 by ditchcrawler

[philjw]

If you don't trust anti freeze testers you could put a sample of your coolant into a domestic freezer.  I believe freezers are somewhere around -18 degrees Celsius.  If the sample freezes then you may have a problem if the ambient temperature drops that low.

I just use a tester like the one linked by Ditchcrawler.

[Morris]

Just went to buy a tester (dial type) , tested it and the pointer was just below the lowest measurement on the scale (12 deg C). I like your idea Phil, but unfortunately we don't have a freezer. (BTW that's a nice dipper in your avatar. Ron hough iinm) 

 

Based on this (the reading, not the dipper) would it be best to drain it down?