Paul;
Buy an anti-freeze tester for the type of coolant you are using i.e. a
regular tester will not work on Seira brand. Then check the protection
offered by the mixture in your vehicle. You should be able to figure out
how much you need to drain and replace  with straight anti-freeze. 
As for damage you are probably OK. 
Good Luck
Ken Lewis
kdlewis@juno.com
86 VW crewcab
85 VW Vanagon GL
60 356 coupe

On Sat, 18 Jan 1997 18:00:29 -0600 Robert Cronin <cronin@meol.mass.edu>
writes:
>My diesel had cooling problems this past summer, but after bleeding, 
>replacing the thermostat, and flushing, everything was A-OK.  Today in 
>the frigid weAther (10-20 f) New problems arose. 
>Paul C 
>82 Diesel Westy
>