Planning on flushing the entire system this weekend on my 79 series II will throw a new thermostat in while I am at it. Is a prestone 50/50 pre mixed product ok to use for refilling? Anyone know the total volume needed to refill?Thoughts on using a flushing chemical or just stick to a few rounds of distilled water?

 

Full strength is better for the purpose. It lets you adjust the strength after
you have been able to add enough as the coolant part of the mix.

Why?

Let's say you have a 12 litre capacity, you flush with water and drain
as best you can.

But, you cannot completely drain the water and you have three quarts
of water left in the system when done.

The most you can get into the system is an additional 9 litres.

If that 9 litres is 50/50 premix, it will be diluted with the remainig
3 litres of water. At that point the strength is less than 50/50.

Someone else will come along who knows the actual capacity.

 

Dont know how often you do this, but be prepared for the thermostat housing to fight you!, unless.of course its different to a series.3, then maybe you will be able.to.just throw a t stat in.