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The debate always rages about winterizing with a dry block or with a block full of Antifreeze (AF). I decided to do a test for myself last November. I took 2 pieces of mild steel cut from the same bar. I lightly roughed them up with 60 grit sandpaper. My first picture shows the 2 pieces at this point.
I then filled a container with Supertech RV antifreeze (Wal-Mart brand) and placed piece A in here and sealed it. This is my simulation for a full engine block.
For piece B, I wetted my hand with tap water and flicked in a very small amount of water into the container. I dipped piece B in undiluted AF and then placed it in the container without wiping it off. This is simulating a block that was filled with AF and then drained. My assumption is that there will always be some water droplets/humidity left over after draining.
I let these containers sit outside under my covered deck for the past 11 months. On 2 occasions, I flicked in some more tap water in the piece B container (dry block simulation).
The next picture shows how the two pieces looked today, right out of the containers. As you can see from the after pics, piece A had spots covered in a grayish sludge. The sludge was pretty firm to the touch and it could be mostly removed with hard scrubbing with a paper towel. Once the sludge was removed, you could feel where the steel surface had actually been eaten away by the AF. I measured the worst spot and it had made a hole .006” deep!
Piece B had a light amount of surface rust showing right out of the container. I was able to scrub some of this off with a paper towel, as can be seen in the after pictures. The rust was purely on the surface. I observed no pitting even under magnification. The rust had built up on the surface only .002” thick.
The Supertech RV antifreeze that I used does not mention any corrosion inhibitors on the label. The MSDS did show "additives", but no idea if they are for corrosion. If they are, they do not work very well. After doing some research, I found info about how uninhibited ethylene glycol will eventually degrade. This degradation produces acids which will corrode iron, steel, copper, and aluminum. The Supertech MSDS says that it contains both ethylene glycol and propylene glycol.
Conclusion – I will never leave my engine full of the Supertech AF again. If I am going to use Supertech or any other uninhibited AF, I will use it to flush my system in order to get out any hidden pockets of water. Then I will drain everything out and store it dry. The uninhibited AF should be fine for the ballast system since the only metal there is the bronze pump head.
I am going to repeat this same test with the Splash brand AF that contains DOW corrosion inhibitors. Peter mentioned this product in another thread. It is available at O’Reillys in my neck of the woods. Using this AF with inhibitors and keeping the block full is most likely the best route to take, if the DOW additives are good. I’ll report back on my testing in a few months.
I then filled a container with Supertech RV antifreeze (Wal-Mart brand) and placed piece A in here and sealed it. This is my simulation for a full engine block.
For piece B, I wetted my hand with tap water and flicked in a very small amount of water into the container. I dipped piece B in undiluted AF and then placed it in the container without wiping it off. This is simulating a block that was filled with AF and then drained. My assumption is that there will always be some water droplets/humidity left over after draining.
I let these containers sit outside under my covered deck for the past 11 months. On 2 occasions, I flicked in some more tap water in the piece B container (dry block simulation).
The next picture shows how the two pieces looked today, right out of the containers. As you can see from the after pics, piece A had spots covered in a grayish sludge. The sludge was pretty firm to the touch and it could be mostly removed with hard scrubbing with a paper towel. Once the sludge was removed, you could feel where the steel surface had actually been eaten away by the AF. I measured the worst spot and it had made a hole .006” deep!
Piece B had a light amount of surface rust showing right out of the container. I was able to scrub some of this off with a paper towel, as can be seen in the after pictures. The rust was purely on the surface. I observed no pitting even under magnification. The rust had built up on the surface only .002” thick.
The Supertech RV antifreeze that I used does not mention any corrosion inhibitors on the label. The MSDS did show "additives", but no idea if they are for corrosion. If they are, they do not work very well. After doing some research, I found info about how uninhibited ethylene glycol will eventually degrade. This degradation produces acids which will corrode iron, steel, copper, and aluminum. The Supertech MSDS says that it contains both ethylene glycol and propylene glycol.
Conclusion – I will never leave my engine full of the Supertech AF again. If I am going to use Supertech or any other uninhibited AF, I will use it to flush my system in order to get out any hidden pockets of water. Then I will drain everything out and store it dry. The uninhibited AF should be fine for the ballast system since the only metal there is the bronze pump head.
I am going to repeat this same test with the Splash brand AF that contains DOW corrosion inhibitors. Peter mentioned this product in another thread. It is available at O’Reillys in my neck of the woods. Using this AF with inhibitors and keeping the block full is most likely the best route to take, if the DOW additives are good. I’ll report back on my testing in a few months.
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