2025 test9 productsEngine Oil & Fluids
Which Engine Coolant Additive Brand Wins?
We compared 9 engine coolant additive options head to head. Red Line SuperCool came out on top. See the measured results, the runner-up, the budget pick, and a link to the full test video.
Winner
Red Line SuperCool
Price shown in test: $50
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Runner-up
Mishimoto Liquid Chill
Price shown in test: $48
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Budget pick
VP Racing Additive
Price shown in test: $16
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The measured results
Every number below is read straight from the test. Scroll sideways to see all measurements. Products are listed in the order they finished.
| Product | Claim | Baseline pH | Reserve alkalinity after one drop of sulfuric acid | Boiling point | Freezing / crystallization | Lubricity wear scar | Heat exchange cumulative temperature difference |
|---|---|---|---|---|---|---|---|
| 1Red Line SuperCool$50 | fortified with water wetter, reduces temperatures by up to 20 degrees F, 50/50 pre diluted antifreeze ready to use, claimed to last 5 years or 150,000 miles | 8.25 | 6.87, third place in this test behind Evans and Liquid Chill | 229 degrees F, better than the unboosted peak antifreeze's 228 degrees F | about two thirds crystallized at the intermediate freezer check around minus 35 degrees F, frozen along with all other coolants except Evans by the final minus 47 degree F check | 6.1 mm, described as performing about as good as Liquid Chill which had the smallest scar of the individually tested additives | 17.1 degrees F, third place behind VP Racing Stay Frosty and Liquid Chill |
| 2Mishimoto Liquid Chill$48 | 50/50 premixed ready to use, claims to reduce engine wear, inhibit corrosion, and seal pinhole leaks, boilover temperature up to 265 degrees F, freeze protection to minus 26 degrees F | 8.14, lower than most of the other brands | 6.9, by far the best reserve alkalinity of the individually tested products, holding the lead over Red Line's 6.87, second place overall behind Evans | 223.5 degrees F, about 5 degrees cooler than the peak antifreeze baseline | a few crystals at the top at the intermediate freezer check, fully frozen along with the other non Evans coolants by the final minus 47 degree F check | 6.09 mm, the smallest wear scar of any product tested, described as coming out on top, with Red Line barely trailing at 6.1 mm | 17.5 degrees F, second place behind VP Racing Stay Frosty |
| 3VP Racing Additive$16 | cool down runs up to 30 degrees cooler, reduces cylinder head temperature by up to 75 degrees F, lubricates all vital components, marketed for racing, street, RVs and tow vehicles | brought the peak antifreeze pH down slightly from 8.47 to 8.32 | 6.44, described as the best yet at that point in testing, tied with Engine Ice's post acid reading | transcript reads roughly 230.1 degrees F in a garbled passage, described as performing about the same as the DEI Relief boosted antifreeze, kept verbatim with ambiguity flagged | about the same crystallization progress as DEI Relief at the intermediate freezer check | 6.4 mm, performed better than the Rislone and DEI Relief boosted antifreeze but not quite as good as the plain antifreeze | 15.5 degrees F, moved into the lead at that point in testing before Engine Ice and VP Racing Stay Frosty were tested |
| 4Rislone Hyper Cool$8 | reduces engine temperature by up to 25 degrees F, up to 75 degrees cooler cylinder head temperature, lubricates and protects water pump seals, helps prevent corrosion of metals including aluminum | 8.47, the same as the unboosted peak antifreeze | 6.39, described as helping strengthen the antifreeze's reserve alkalinity a little versus the unboosted antifreeze's 6.26 | 233.36 degrees F, second place behind Evans Waterless overall in the boiling point test, though this specific figure is only given in the closing summary rather than the individual product breakdown | just a few crystals at the top at the intermediate freezer check, frozen by the final minus 47 degree F check | 6.42 mm, a small amount larger (worse) than the plain antifreeze's 6.36 mm | 14.4 degrees F |
| 5DEI Relief$10 | allows the engine to run up to 30 degrees cooler, combats electrolytic and chemical corrosion, reduces existing scale buildup, protects against radiator core damage | 8.57 | 6.42, moved into the lead at that point in testing ahead of Rislone | transcript reads roughly 231 degrees F in a garbled passage (captured as 23.1 in the raw transcript), kept with ambiguity flagged, described as not performing quite as well as Rislone | top third crystallized at the intermediate freezer check | 6.48 mm, trailing Rislone's 6.42 mm by a small amount | 14.3 degrees F, about the same as Rislone |
| 6Royal Purple Ice$17 | up to 25 degrees F cooler, fights corrosion, electrolysis, and erosion, contains lubricant to protect the water pump | lowered the peak antifreeze pH slightly from 8.47 to 8.42 | 6.51, moved into the lead at that point in testing | 228.5 degrees F, about the same as the unboosted antifreeze | close to the same crystallization progress as VP Racing Additive at the intermediate freezer check | 6.4 mm, tied with VP Racing Additive | 15.2 degrees F, moved into second place at that point in testing |
| 7Engine Ice$26 | boilover protection up to 26 degrees F and freeze protection to minus 28 degrees F per the product label, which the presenter notes had little other information printed on the container | 9.04, the highest baseline alkalinity of any product tested | 6.44, tied with VP Racing Additive | 225.4 degrees F, lower than the peak antifreeze baseline | the first ready to use coolant to fully freeze solid, around minus 32 degrees F at the intermediate freezer check | 6.49 mm, a little more wear than most other products at that point in testing | 16.2 degrees F, moved into the lead at that point in testing |
| 8VP Racing Stay Frosty$34 | 100 percent water based formula that will not protect against freeze ups, claims to reduce engine temperatures by up to 30 degrees F and meet ASTM corrosion standards, contains lubricant to protect the water pump | right at 8, the least alkaline baseline of any product tested | 5.84, the most acidic result of any coolant tested | transcript reads roughly 22.4 degrees F in a garbled passage, described as boiling very close to the same temperature as plain water, kept verbatim with ambiguity flagged since the literal digits do not match a plausible boiling point | the first product to fully freeze, already completely frozen at the initial minus 27 degree F freezer setting, before the freezer was even made colder | 6.45 mm, slightly better than Engine Ice | 19 degrees F, the best of any product tested in this specific test |
| 9Evans Waterless$52 | high performance waterless engine coolant, claims to boil over at 375 degrees F, protect to minus 40 degrees F, eliminate engine hot spots, fight corrosion, and lower pressure | 8.42, very close to the peak antifreeze baseline | 7.9, by far the best of any product tested | 388 degrees F, by far the best of any product tested, over 100 degrees F better than the competition | still in liquid form at the final minus 47 degree F freezer check when every other coolant, including the plain peak antifreeze, had frozen; presenter concludes its crystallization point is colder than minus 47 degrees F | described only as clearly worse (larger) than Red Line's 6.1 mm, no exact figure given | 10.4 degrees F, performed close to the same as a regular unboosted antifreeze, the worst heat exchange result among the ready to use coolants |
How it was tested
- baseline pH and reserve alkalinity after one drop of sulfuric acid added to 50 mL samples
- boiling point measured with a certified thermometer on about 150 mL samples
- freezing / crystallization point in a freezer stepped from minus 27 F down to about minus 47 F over several hours
- lubricity wear scar size in mm on a lubricity tester pin under a microscope
- heat exchange performance measured as cumulative temperature drop in F across a heater core test rig at three points
“the redline super cool came in on top with the best average finish of 3.2”