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West Marine antifreeze

May 6, 2010
465
1984 Oday 39 79 Milwaukee
Just finished winterizing my engine with West Marine premium Marine antifreeze rated to -60. This is a polypropylene glycol antifreeze and when I finished I tested some of the exhaust discharge with the antifreeze in the bottle to make sure what was in the system was full strength. According to my refractometer both are rated to +10 degrees! I calibrated my refractometer and tested again with the same result. I then tested some green ethylene glycol anti-freeze I had on the boat and got the correct reading for that. I am familiar with using the refractometer and am aware there is a scale for both types of antifreeze and I am reading the correct scale. Not sure what explanation there may be but I think I will be re-doing the process with a different product.
 
Jan 11, 2014
7,849
Sabre 362 113 Fair Haven, NY
Thanks for the heads up. I'll be checking my jugs of WM AF. I use ethylene glycol in the engine, so I'm not worried about that.
 
May 6, 2010
465
1984 Oday 39 79 Milwaukee
I'm wondering if it's reading the slushing point which is 7 degrees? It says on the bottle slushing protection starts at 7 but it freeze protects to -60. I'm feeling a little less confident about my protection.
 
Jan 11, 2014
7,849
Sabre 362 113 Fair Haven, NY
The issue with freezing is freezing solid. As water freezes it expands, the AF keeps the water from freezing solid and thus keeps it from expanding and causing damage. However, the slush will damage pumps if the pump is run with slush in the line.

A while back Maine Sail had a post here on his website about this with photos of a gallon of AF he left outside in a Maine winter.

One option you have is to drain he heat exchanger and drain the muffler. Unless you have seawater cooled engine. When I had a seawater cooled Volvo MD7A I would drain the block after flushing with AF. There may have been some residual AF in the block, but there was plenty of space for any ice to expand into. No problems for the 15 years I owned the boat.
 
Sep 25, 2008
6,315
Alden 50 Sarasota, Florida
Unlike ethylene glycol designed to be mixed with water, the efficacy of p-glycol is effected by dilution with water which you likely didn’t intend because it mixed with residual water either in the engine or water-lift muffler.
 
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May 6, 2010
465
1984 Oday 39 79 Milwaukee
Unlike ethylene glycol designed to be mixed with water, the efficacy of p-glycol is effected by dilution with water which you likely didn’t intend because it mixed with residual water either in the engine or water-lift muffler.
I understand that, which is why I noted that I tested the exhaust discharge against the straight solution from the bottle, and the results were the same. The whole point of the exercise was to determine that I had undiluted solution coming out the exhaust which appears to be the case. The unintended consequence of the exercise was the discovery that the refractometer reading is not what I had anticipated.
 
Mar 26, 2011
2,937
Corsair F-24 MK I Deale, MD
Just finished winterizing my engine with West Marine premium Marine antifreeze rated to -60. This is a polypropylene glycol antifreeze and when I finished I tested some of the exhaust discharge with the antifreeze in the bottle to make sure what was in the system was full strength. According to my refractometer both are rated to +10 degrees! I calibrated my refractometer and tested again with the same result. I then tested some green ethylene glycol anti-freeze I had on the boat and got the correct reading for that. I am familiar with using the refractometer and am aware there is a scale for both types of antifreeze and I am reading the correct scale. Not sure what explanation there may be but I think I will be re-doing the process with a different product.
a. There was likely some water in the system.

b. The -60F rating is BURST POINT, not freeze point. Look at the bottle. The freeze point is about 0-10F with no water added.

So this is normal. Many people are confused by this each winter. If you live where temperatures below 10F are common, I suggest stronger AF, since the "burst point" claim is...
1. based on copper pipe. plastic and cast are weaker than that.
2. for a single freeze cycle. If there is repeated freezing in a complex system (engine), the ice floats to the top creating a layer of very weak AF in the cylinder head. Your funeral. I've seen heads burst and long vertical pipes burst (at the top).

Don: EG and PG are basically the same in this regard, except PG is very, very slightly less effective. But not the way you describe. The difference is packaging and labeling.

[Many years as a chemical engineer in the glycol business]
 
Last edited:
Sep 25, 2008
6,315
Alden 50 Sarasota, Florida
a. There was likely some water in the system.


Don: EG and PG are basically the same in this regard, except PG is very, very slightly less effective. But not the way you describe. The difference is packaging and labeling.
In a former life, I was a chem engineer too. I think you ‘nailed’ it in the first sentence.
 
May 6, 2010
465
1984 Oday 39 79 Milwaukee
In a former life, I was a chem engineer too. I think you ‘nailed’ it in the first sentence.
Don you've said that a couple of times now, and I would be inclined to agree but for the fact the antifreeze in the exhaust discharge reads exactly the same as the fresh antifreeze still in the jug.
 
May 17, 2004
3,483
Beneteau Oceanis 37 LE Havre de Grace
Here’s another data point - I just checked a brand new unopened Starbrite -50 PG bottle. It’s dated from October , after their recalled batch ended. Here’s what I saw -

1604175762900.jpeg


Closer to 25% than 30%. Freezing point around 13 degrees!?

I checked an old bottle of Camco I had from last year (which may have even been out of my water heater after it was purged, I’m not sure) and it was right on the 30% line. I double checked with distilled water and the calibration was spot on.
 
May 17, 2004
3,483
Beneteau Oceanis 37 LE Havre de Grace
Here’s another data point - I just checked a brand new unopened Starbrite -50 PG bottle. It’s dated from October , after their recalled batch ended. Here’s what I saw -

View attachment 186774

Closer to 25% than 30%. Freezing point around 13 degrees!?

I checked an old bottle of Camco I had from last year (which may have even been out of my water heater after it was purged, I’m not sure) and it was right on the 30% line. I double checked with distilled water and the calibration was spot on.
I did find on the Starbrite product page that “When testing with a refractometer or with a hydrometer designed for use with PG, freeze point readings on the PG scale will range from +14°F to +18°F.” So I guess mine is in spec.
 
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May 6, 2010
465
1984 Oday 39 79 Milwaukee
I did find on the Starbrite product page that “When testing with a refractometer or with a hydrometer designed for use with PG, freeze point readings on the PG scale will range from +14°F to +18°F.” So I guess mine is in spec.
I believe the West Marine branded anti-freeze is manufactured by Starbrite.
 
Oct 22, 2014
16,130
CAL 35 Cruiser moored EVERETT WA
Without information from Starbrite the cause of the recall is not identified. It may spec correctly for its temp properties, but there may be some contaminants that cause other issues.
 
Mar 26, 2011
2,937
Corsair F-24 MK I Deale, MD
Here’s another data point - I just checked a brand new unopened Starbrite -50 PG bottle. It’s dated from October , after their recalled batch ended. Here’s what I saw -

View attachment 186774

Closer to 25% than 30%. Freezing point around 13 degrees!?

I checked an old bottle of Camco I had from last year (which may have even been out of my water heater after it was purged, I’m not sure) and it was right on the 30% line. I double checked with distilled water and the calibration was spot on.
Yes, that is normal. The spec is typically 26-27%.

to repeat from above:

Many people are confused by this each winter. If you live where temperatures below 10F are common, I suggest stronger AF, since the "burst point" claim is...
1. based on copper pipe. plastic and cast are weaker than that.
2. for a single freeze cycle. If there is repeated freezing in a complex system (engine or water system), the ice floats to the top creating a layer of very weak AF in the cylinder head or other high spots. Your funeral. I've seen heads burst and long vertical pipes burst (at the top).