Antifreeze: Which type is best?

[Breakin Away]

Guys : I'm absolutely baffled by a quest for the "BEST Anti freeze"?? 
I always thought that there were really only a couple of characteristics that you needed to for in anti freeze - at what low temperature does the mixture start to congeal, water-pump lubrication, rust inhibitor and some longevity (lasts more than a year before breaking down).  Most major brands profess they have these characteristics??!!

Also I'm interested in "who" it is that did all of the testing to decide "which" is the best!! Their criteria and test parameters??
Also It would seem to me that the "water (cooling) jacket" in any engine (spark or compression) is about the same. Temperature of approx 160 degrees also should be the same in our small diesel engines or small gasoline engines. Temp. Might be much higher in large truck engines?!? Probably be a difference depending on the metal that the engine block is cast out of.

A few thoughts

I'm coming back to this after a few months as I am working on spring commissioning.

Practical Sailor has done quite a bit of testing on diesel antifreeze over the years.

I haven't re-read everything from a few months ago, but IIRC the "best" antifreeze for diesel engines includes cavitation inhibitors that reduce cavitation pitting of the cylinder shells. This is not necessary in gasoline engines due to lower compression ratios, but on diesels the higher compression/vibrations can make that a factor. Since I'm due for a full antifreeze replacement, I'm going with Zerex G-05 HOAT, which tested well, is reasonably priced, and readily available.

I'd still like to do a mild acid wash of the freshwater cooling system (run it for 15 min or so, then rinse with water and fill with new antifreeze), and would like any advice on what I could use. Rydlyme is not readily available around here. I could try Barnacle Buster. What about cleaning vinegar? oxalic acid? diluted CLR?

I'd also like to do an acid clean of the raw water side of my HX. I'm thinking of removing my pencil anode and replacing it with a hose barb (1/4" NPT thread). Then I could either pump in/out some acid (displaced air would vent out the exhaust hose) using a portable impeller, or even just gravity feed the acid through a raised funnel/tube connected to the hose barb. The latter method has the advantage of giving me a lot of control over the exact amount needed, since I just put the funnel about an inch above the HX to fill the HX without overfilling into the other components. Once again, I'd appreciate advice of what, other than Rydlyme, I could use for this (cleaning vinegar/oxalic acid/CLR)

[lazybone]

Guys : I'm absolutely baffled by a quest for the "BEST Anti freeze"?? 
I always thought that there were really only a couple of characteristics that you needed to for in anti freeze - at what low temperature does the mixture start to congeal, water-pump lubrication, rust inhibitor and some longevity (lasts more than a year before breaking down).  Most major brands profess they have these characteristics??!!

Also I'm interested in "who" it is that did all of the testing to decide "which" is the best!! Their criteria and test parameters??
Also It would seem to me that the "water (cooling) jacket" in any engine (spark or compression) is about the same. Temperature of approx 160 degrees also should be the same in our small diesel engines or small gasoline engines. Temp. Might be much higher in large truck engines?!? Probably be a difference depending on the metal that the engine block is cast out of.

A few thoughts

I'm coming back to this after a few months as I am working on spring commissioning.

Practical Sailor has done quite a bit of testing on diesel antifreeze over the years.

I haven't re-read everything from a few months ago, but IIRC the "best" antifreeze for diesel engines includes cavitation inhibitors that reduce cavitation pitting of the cylinder shells. This is not necessary in gasoline engines due to lower compression ratios, but on diesels the higher compression/vibrations can make that a factor. Since I'm due for a full antifreeze replacement, I'm going with Zerex G-05 HOAT, which tested well, is reasonably priced, and readily available.

I'd still like to do a mild acid wash of the freshwater cooling system (run it for 15 min or so, then rinse with water and fill with new antifreeze), and would like any advice on what I could use. Rydlyme is not readily available around here. I could try Barnacle Buster. What about cleaning vinegar? oxalic acid? diluted CLR?

I'd also like to do an acid clean of the raw water side of my HX. I'm thinking of removing my pencil anode and replacing it with a hose barb (5/16" UNC, if I can find it?). Then I could either pump in/out some acid (displaced air would vent out the exhaust hose) using a portable impeller, or even just gravity feed the acid through a raised funnel/tube connected to the hose barb. The latter method has the advantage of giving me a lot of control over the exact amount needed, since I just put the funnel about an inch above the HX to fill the HX without overfilling into the other components. Once again, I'd appreciate advice of what, other than Rydlyme, I could use for this (cleaning vinegar/oxalic acid/CLR)

I would like to read more about how antifreeze additives inhibit cavitation in combustion cylinders.  Could you direct me to your source?  Or maybe I misunderstood your post.

[Breakin Away]

I would like to read more about how antifreeze additives inhibit cavitation in combustion cylinders.  Could you direct me to your source?  Or maybe I misunderstood your post.

It's not in the cylinders, but outside the liners. Caused by ultrasonic waves from the high pressure "explosions" of diesel combustion. This article describes the issue:
https://www.practical-sailor.com/boat-maintenance/coolants-that-fight-corrosion

Regarding my prior inquiry about finding an economical acid cleaner for flushing my raw water and freshwater (coolant) systems, I am concerned about using a raw, uninhibited acid in my engine (acetic, oxalic, muriatic, citric, etc.). But there are dozens of pre-formulated products sold for automotive applications that need to strike the same balance of effectiveness against minerals vs. inhibition against attacking the metal components. Is there any reason not to flush with a Prestone (or similar) radiator cleaner instead of Rydlyme?

[Noah]

IMO —Breakin' — you are way over-thinking it... as the Practical Sailor article says " If you run your engines hard for over 1,000 hours per year-commercial fishing, perhaps-then SCAs should be a part of your maintenance program. If you barely burn a tank of fuel each season, you will be fine replacing the coolant every five years." I say go with a typical brand name  "green poly glycol" stuff and forget about it. Caveat: I am NOT a mechanic.

[Breakin Away]

IMO —Breakin' — you are way over-thinking it... as the Practical Sailor article says " If you run your engines hard for over 1,000 hours per year-commercial fishing, perhaps-then SCAs should be a part of your maintenance program. If you barely burn a tank of fuel each season, you will be fine replacing the coolant every five years." I say go with a typical brand name  "green poly glycol" stuff and forget about it. Caveat: I am NOT a mechanic.

I suggest you re-read the article, especially the paragraph before the one you quoted. They describe a maintenance program of regularly replenishing the SCAs with supplemental additives. Such frequent (annual or more) replenishment of the SCAs is only needed if you put on 1000 hours a year. For the rest of us, replacing the coolant every five years is good enough. That's what they're actually saying.

And their conclusion is "If you have a diesel engine, you are safer with a diesel product, something that is formulated to handle the diesel clatter." In other words, use a heavy duty coolant formulated with SCAs for diesel engines. Pick one from their list - I chose Zerex G-05.

I've also had discussions about this in other forums with Drew Frye (who was involved in the Practical Sailor testing) and Maine Sail. Neither says that our diesels are going to explode from using normal green stuff, but I'm due to replace my coolant anyway, so I have no reason not to go with Zerex G-05, and have some data that says it would be beneficial. The "corrosion" column of Practical Sailor's test lineup makes the difference pretty clear.

[Noah]

Whatever works for you. Mine has been running "green" for past five years and the previous owner used same for five years before—-don't know what was used before way back to 1990. But, do know my 25XP engine runs fine, with no apparent issues (Hope this doesn't jinx it  )

[lazybone]

I would like to read more about how antifreeze additives inhibit cavitation in combustion cylinders.  Could you direct me to your source?  Or maybe I misunderstood your post.

It's not in the cylinders, but outside the liners. Caused by ultrasonic waves from the high pressure "explosions" of diesel combustion. This article describes the issue:
https://www.practical-sailor.com/boat-maintenance/coolants-that-fight-corrosion

Regarding my prior inquiry about finding an economical acid cleaner for flushing my raw water and freshwater (coolant) systems, I am concerned about using a raw, uninhibited acid in my engine (acetic, oxalic, muriatic, citric, etc.). But there are dozens of pre-formulated products sold for automotive applications that need to strike the same balance of effectiveness against minerals vs. inhibition against attacking the metal components. Is there any reason not to flush with a Prestone (or similar) radiator cleaner instead of Rydlyme?

Thank you for that.  I also found some other articles.  "Down the rabbit hole"

[Ron Hill]

Guys : After all that - think I'll just sail in and out of my slip!!  or just stay at the dock and work on the teak!!   

A thought

[Breakin Away]

First, I want to reiterate that our Universal diesels will probably be just fine with ordinary green glycol coolant. I'm going with the Zerex out of abundance of caution, but I think most of the "ringing" cavitation issues happen with diesels with different designs from the Universal. But the G-05 can't hurt, might last longer, and was on sale for a very reasonable price.

Regarding my coolant replacement plan, I think I'm just going to go with a distilled water rinse and re-fill. I have no discoloration or other indications of corrosion. The commercial cleaners appear to be just 10% sodium citrate, which as far as I can tell isn't a cleaner at all, but more of a weak base to neutralize acid buildup from old antifreeze. It seems like old fashioned acidic cleaners are no longer found in auto stores due to the proliferation of delicate aluminum radiators and environmental concerns. So I'm going to stop over-thinking it and just rinse and replace.

[Breakin Away]

Just to close out this issue, I completed the distilled water rinse and coolant replacement a couple weeks ago. I had some minor issues with air pockets and establishing the siphon from the coolant reservoir, but resolved them using a portable electric impeller pump recirculating through the hot water heater (pump from from full exhaust manifold and pump into hose removed from nipple of water pump while plugging the nipple) and then removing the reservoir tube from the exhaust manifold and pumping back into the reservoir to eliminate air pockets in the high spots of the feed tube.

Regarding the use of Zerex G05, I had heard it referred to as "yellow" so was expecting it to have some bright yellow dye. Instead, I'd call it more of a faint "amber" color which make it tough to distinguish from other fluids. If you see a little pink or green liquid in the bilge or other low spots, you immediately know what fluid it is. With the Zerex, you can't really tell if it's seawater, freshwater, or coolant. On the plus side, it is much more transparent than the green liquid, so I expect that it will be easier to detect if there is any precipitate in the coolant reservoir or exhaust manifold.

I've put 15 hours on the motor in the past 2 days, and it ran great and held temperature under load.

[Ron Hill]

Guys : Always use distilled water in your anti freeze mix because you don't know the mineral content in tap water!!!

I've been lucky as I have an old 1948 GE fridge in the garage along side of a 1965 Sears freezer.  Both need defrosting periodically, so I have a ready made source of distilled water!!  It's amazing that that GE fridge defrosts in short order by reversing the "cooling" cycle!  And they say that old stuff wasn't engineered!!   

A thought