Hi All
Three of the reasons I have always heard for using a 50/50 mix of antifreeze are:
- Freeze protection down something like -35C even then it doesn't freeze like water hard but instead the water starts to separate out as ice crystals making a mush which doesn't pump through the engine very well.
- Rust inhibitor, which depending on your local water can be very important in preventing rust. In the US even rain water may be acetic particularly in the North East.
- Higher boiling point a 50/50 mix of antifreeze even in a non-pressurized system has a significantly higher boiling point than just plain water. Going to one of the company data sheets they list boiling point as being 107C (226F)
and freeze point as -37C (-34F) for 50/50 mix.
On one occasion when setting up a new engine 261cu.in. for my C60S I didn't use antifreeze or rust inhibitor while I was testing the engine and had significant rust damage to the water pump adapter plate in a very short period of time. Rust pitted the plate to the point that it had to be replaced because of a weeper leak in the sealing surface. Lesson learned now I always use either rust inhibitor or antifreeze any time I fill a cooling system.
I have also seen the difference in cooling once when having a cooling problem on my Pat 12 C60L as I blew water out of the system because of overheating and replaced it on the move with a pressure pump putting water back into the system the overheating kept getting worse and worse as the antifreeze in the engine was gradually replaced by plain water.
Cheers Phil