Coolant is a bit like engine oil, in that most car owners have their personal favorite. It is really debatable if there is a significant or even noticeable difference between quality coolants and antifreezes. If we lived in a world where we could have ideal testing conditions — using our top recommendations in different instances of the same vehicle with the same conditions for 100,000 miles, for example — we might be surprised by the results. But unfortunately we don’t live in that world and conducting a simulation like that is impossible.
So how do we go about deciding the best antifreezes and coolants? Our top choices come from a mix of personal experience and scouring the internet and forums for advice from actual Porsche owners and experts. The products seen on this list all come highly recommended from Porsche enthusiasts, some who have used these products in their vehicles for over 150,000 miles.
1. Top pick: Zerex G40 by Valvoline
Throughout my research, I found many Porsche owners who recommend Zerex G40 by Valvoline. This 50/50 prediluted antifreeze is coolant that’s ready to be used in your Porsche or other vehicles from German automakers Audi, Mercedes-Benz, and Volkswagen. It’s a phosphate- and nitrate-free formula, an important factor when shopping for Porsche coolant.
As its name suggests, this coolant is designed for European vehicles requiring genuine G40 or G12++ coolant. It uses a premium Si-organic acid technology formula for long-life protection and it meets several industry specifications: ASTM D3306, ASTM D4985, ASTM 6210, Federal Specification A-A-870A, SAE J1034, J814, and J1941.
Valvoline says this coolant will provide protection for 5 years / 150,000 miles in light duty applications, or 3 years / 300,000 miles in heavy duty applications.
If you happened to come across this post and you don’t own a Porsche, Zerex is still our recommendation for the best coolant. It comes in different applications that work with a wide variety of vehicles, so find the right one for your specific car.
2. Runner-up: PEAK OET Violet
Another popular favorite among Porsche owners is this Violet 50/50 prediluted coolant from PEAK’s Original Equipment Technology (OET) lineup. The Violet version is designed for European vehicles that require a silicate-enhanced organic acid technology (Si-OAT) formula and covers 2007-up Audi, 2014-up Mercedes-Benz, 2009-up Porsche, and 2008-up Volkswagen. If your vehicle doesn’t land in that list, make sure to check out the other PEAK OET coolants that are available.
Like our top pick, this coolant is prediluted and ready to go. If you install it as part of a complete flush and fill — which you should — PEAK will guarantee the coolant to provide service life protection up to 150,000 miles or 5 years.
According to PEAK, this coolant will protect from -34°F to 265°F. In my research, I came across dozens of posts with Porsche owners who recommended this coolant, saying it’s a cost-effective alternative than buying genuine Porsche coolant from the dealership.
3. Pentosin Pentofrost SF
Pentosin’s Pentofrost SF was mentioned several times in my research and unlike our other recommendations, this comes as a full strength antifreeze concentrate so you’ll have to dilute it with a 50/50 mixture of distilled water. It’s designed for 1996-up Porsche Boxster, 911, Cayman, and Cayenne models, but will also work on various Audi, Jaguar, Land Rover, Saab, and Volkswagen vehicles.
The freezing point of this coolant once mixed with water is -34°F, while the boiling point is 228.2°F. Like all of our recommendations, this antifreeze concentrate doesn’t contain any nitrites, amines, silicates, or phosphorous containing additives. It does meet ASTM D-3306.
I found that many owners in Europe prefer the Pentosin Pentofrost SF, which makes sense since Pentosin is based out of Germany. As a result, it’s not quite as affordable for U.S. consumers, but it is available.
4. Prestone antifreeze + coolant
Our final coolant recommendation is none other than Prestone’s antifreeze + coolant. It’s a prediluted 50/50 mixture so it’s ready to use, and it’s designed for all vehicles. This is essentially the coolant you’ll find on the shelves of your local auto parts store and is generally used by a lot of vehicle owners since Prestone is a well-known brand.
This is designed to work with all fluid colors, including all OAT, POAT, HOAT, and IAT. Prestone also promises a 10 year/300,000 mile guarantee. For marketing jargon, this product has Prestone’s CorGuard technology, which the company says is its best advancement in cooling system parts protection.
So who recommends Prestone? Many of the Porsche owners who don’t buy into the belief of paying a premium for coolant. I found numerous owners who switched to Prestone coolant for their Porsche and have had no issues with the product. I have also used this coolant in the past on my vehicles and have no complaints. It may seem generic, but it’s a quality product that will do the job for most car owners.
5. Bonus: Red Line Water Wetter coolant additive
We had a difficult time finding a fifth recommendation from Porsche owners for the best antifreeze or coolant. We did however, find many users mentioning the use of Red Line’s Water Wetter, a coolant additive. According to Red Line, it’s a unique agent for cooling systems that doubles the wetting ability of water. With this product, car owners can use straight water in racing conditions, or reduced antifreeze levels in warm climates. It can be used with new or used antifreeze and can reduce coolant temperatures by as much as 30°F.
Red Line Water Wetter is popular among sports car enthusiasts and weekend track warriors. If you own a modern Porsche and simply use it for daily commutes, you likely won’t see much of a benefit from using this. But if you own an older Porsche that tends to run hot, this could help reduce your temperatures.
What is the difference between coolant and antifreeze?
When it comes to shopping for coolant or antifreeze, it can get a bit confusing if you don’t understand the difference between the two products. What you need to understand is that antifreeze is highly concentrated and needs to be diluted with water. When you see 50/50 prediluted antifreeze, that is coolant. Basically, coolant is the product of mixing water and antifreeze.
Can I mix coolants and or antifreezes?
You should never mix coolants or antifreezes. If you’re going to top off your coolant, make sure you use the same type that’s already in the system. Mixing can possibly cause engine damage. If you want to change to a different type of coolant or antifreeze, you’ll need to flush your system.
How often should I flush my system?
The proper answer to this question is to consult your owner’s manual or contact your dealership to determine the correct coolant change interval for your vehicle. The generic answer to this question is every 30,000 miles. However, this may not be true for newer vehicles, which is why we recommend consulting your manual for the accurate answer.
Why do coolants come in different colors?
If you don’t own a Porsche but still want to use one of our recommendations, you may have noticed while shopping that antifreezes and coolants come in a variety of different colors. To give you a breakdown, we’ll reference Zerex’s color code:
- Green: Inorganic Additive Technology (IAT) – designed for older vehicles
- Orange: Organic Acid Technology (OAT) – GM, Saab, VW
- Yellow: Hybrid OAT (HOAT) – Ford, Chrysler, European
- Turquoise: HOAT, phosphate-free – BMW, Volvo, Tesla, Mini, and others
- Pink/Blue: Phosphated HOAT (P-HOAT) – Toyota, Nissan, Honda, Hyundai, Kia, and other Asian vehicles
- Purple/Violet: Silicated HOAT (Si-OAT) – Mercedes-Benz, Audi, VW, Porsche, and others
Generally, the different colored coolants or antifreezes use different inhibitor technologies. Certain products will be made for specific vehicle makes, so make sure you get the right coolant for your car.