Originally Posted by cosmomiller

That explains why my stock car has remained tight over the years. The hose look and feel brand new. Nothing like the American cars of the 60s and 70s.

They grabbed the mule and cut some hair off the mane. They mixed heavy grease in it and shoved it into the hole with a screwdriver until they could do no more. Filled it up with water and away we went back to San Diego. It held pressure until we got a new radiator!

Originally Posted by Car Analogy

Careful, as you're likely changing ratio of coolant vs water over time.

It might not be a surprise that coolant molecules are more complex than water (h2o), and therefore larger in size. So most of the evap through silicone hoses is water.

So if topping off with premix 50/50 coolant, over time you've got less and less water. Since cast majority of cooling comes from water, not coolant, you're cooling capacity is declining.

You'd need to sometimes top off with just water. But how often would require testing, like w hydrometer.