Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Coolant system flush and antifreeze change.

Working on the principle that it's always best to check your work, let's first understand the advice given by the antifreeze manufacturer themselves.

Prestone say a 50/50 mix of thier antifreeze (concentrate) and water will protect Monty's engine down to approximately -37°C, they also say for optimal performance and corrosion protection, it is recommended to use deionized or distilled water when mixing the concentrate. They then go on to say users should not allow the concentration of antifreeze to fall below 40%, or exceed 60% as engine parts could become damaged.

With all that understood, let's see what what my old school specific gravity type tester says?



I'm seeing a reading that's in the middle of -29c and -37c here, so that would be a true reading of -33c. Ok, so it's not quite the -37 quoted by Prestone, but the gauge doesn't offer the most defined indecies so I could actually be at -34c or even -35c depending on how I hold and view it, either way it's clear my dilution is certaily well above the recomended 40% minimum.

My tester also states for protection down to -34 you need a 50/50 mix, so if anything, and being hyper critical here, I must only be a tiny fraction under the optimal 50/50 mix.



Gven this, and the fact Monty doesn't live in Alaska, I'm confident being protected down to at least -33c is more than sufficient, and the dilution I carefully calculated is, 'as near as damn it', perfect