2007 Classic (early) 5.3/4L60E in my 1948 Chevy 3100 with new 3 core brass radiator. Cast iron block with aluminum heads. Should I use the older style green coolant or the newer yellow coolant?

 

The answers you are going to get are going to be all over the board, but I always use the old green stuff and haven't had any issues with it. I tried Dexcool once, but unless your system is completely sealed, anywhere air can get to it it will turn to mud. Haven't used the yellow stuff, which I believe is what Ford uses, so cant say about that.

 

I would use the green stuff with the brass radiator.

Like said above coolant got flipping complicated. But when I checked it out a few years back I convinced myself the green stuff was a better match with the old style, non aluminum radiators and heater cores.

You will need to change it more often since the corrosion inhibitors don't last as long as the newer stuff.

 

Here in Florida it never freezes, so I only recommend we use 10-15% green coolant, and the rest distilled water. Water does a better job at cooling than coolant, it has a higher heat capacity (it absorbs more energy without increasing in temp as quickly) so the natural, logical choice is to use as little coolant as possible.

Furthermore, if the vehicle is very old, and has a sketchy past, I would like to frequently flush at first, so having NO coolant (0% coolant for a few days) helps make it easy, because then you can just drain the 100% distilled water into the parking lot and re-fill, then repeat until it looks normal again (like plain water and not discolored muck).


As a general precaution, Never mix the colors of coolant. Sometimes the bottle will say its ok to mix them though, so just be aware of that.
Also Never use tap water, or drinking water, which contains ions that facilitate electrical continuity which leads to electrolysis and corrosion.

 

Preventing freezing is only part of the reason for antifreeze. You need closer to a 50% mix for the corrosion inhibitor and to lubricate the water pump.

The corrosion inhibitors age, that is the only reason antifreeze needs to be changed out, so running less than a 50% mix means you will need to replace the stuff at more frequent intervals.

 

"The corrosion inhibitors age, that is the only reason antifreeze needs to be changed out, so running less than a 50% mix means you will need to replace the stuff at more frequent intervals."
We use RMI 25 in all our hotrods, tow vehicles,,,Real inhibitors, keeps the crud from forming.