We consider a cooling system additive to be a worthy investment in the long run. Let’s take you step by step, type by type, and find the best cooling system additive for you.

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Our Top Picks:

Best Overall: Buy: Ford Cooling System Additive READ REVIEW

Best For Head Gasket: Buy: Subaru Cooling System Additive READ REVIEW

Best For Leaks: Buy: K-Seal Cooling System Additive READ REVIEW

Best For Fast Delivery: Buy: Motorcraft Cooling System Additive READ REVIEW

Best For Reducing Engine Temp: Buy: Red Line Cooling System Additive READ REVIEW

Best With Great Stuff: Buy: Mishimoto Cooling System Additive READ REVIEW

Best With All Types: Buy: Bars Leaks Cooling System Additive READ REVIEW

Compatible With Water: Buy: Design Engineering Cooling System Additive READ REVIEW

Best Coolant: Buy: Evans Cooling System Additive READ REVIEW

Best Overall: Ford Cooling System Additive

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The Ford Cooling System Additive is capable of outshining several other additives featured in this list in overall features. Also, the additive is designed to replace additives depleted between coolant change-outs. Now dyed yellow to eliminate engine coolant color change when mixing. Lastly, the ford cooling system additives are on hand and it works well.

Almost all buyers quickly discovered that the additive protects your engine against cavitation. Also, a few strongly agree that this is a motorcraft branded additive for ford f250 7.3 diesel motor oil to prevent cavitation. In conclusion, for almost all buyers, it was what they were looking for.

• Replaces fluorescent green-colored v119 premium antifreeze/coolant meeting ford specification ese-m97b44-a.
• What can be said it is an anti-cavitation/corrosion fluid additive.
• Replaces yellow-colored motorcraft gold antifreeze/coolant meeting ford specification wss-m97b51-a1.

Best For Head Gasket: Subaru Cooling System Additive

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Next on the list, we've got yet another additive that manages to win our hearts. It's the Subaru Cooling System Additive and it's widely considered as one of the most convenient additives you can buy. Helps prevent corrosion in your subaru's cooling system. Further, the additive is manufactured to subaru standards, oem subaru parts, not after market parts, genuine subaru parts and accessories. To sum up, with a 4.6 rating and more than 7864 buyers, the subaru cooling system additive stands as the best choice.

Almost all buyers agree that the additive is to be added to coolant in specific subarus. Further, a few say that the additive is great insurance as a coolant conditioner and water pump conditioner. Also, they strongly agree that Subaru recommended stopping the leak since Rubies are known for their head gasket issues. To sum up, the tone of buyers is very positive and we believe that the additive suits the purpose.

• This is particularly the case in 2000.
• The combustion pressure will not allow the sealer to seep in.
• This is used for the 2001 Camry le internal leak.
• This used to be used as an old-time fix.

Best For Leaks: K-Seal Cooling System Additive

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Next on the list, we've got yet another additive that manages to win our hearts. It's the K-Seal Cooling System Additive and it's widely considered as the additive that has the most suitable features. The k-seal cooling system additive is trusted by millions of customers worldwide, and is the only coolant leak repair fluid carried by aa, the uk’s largest roadside repair company. Coolant leaks do result in costly repair bills. And, it is leaking from the system, either externally or internally across the head to the cylinders, then k-seal will follow it through the hole or crack and try to fix the leak.

Lastly, the k-seal cooling system additive is used for engine blocks, is made for cracks in the radiator and it provides great value.

Most customers agree that the additive has been about 6k miles without a problem. Moreover, a few say that the additive is so simple and easy to use. Further, they also found that the coolant / k - seal mixture instantly clogged up and broke the pump. Consequently, customers were eager to recommend it to friends and families.

• This has dripped onto hot engine parts and disappeared within minutes.
• This protects occupants during a crash.
• This is well worth the money to try.
• Permanent coolant leak repair - just shake, pour and go.

Best For Fast Delivery: Motorcraft Cooling System Additive

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The Motorcraft Cooling System Additive is suitable and reliable and fits well with your daily purpose. The motorcraft cooling system additive is designed to replace additives depleted between coolant change-outs. In all heavy-duty, diesel engine cooling systems equipped with green-colored motorcraft premium engine coolant meeting ford specification ese. This product contains less than 10 % ethylene glycol or contains a bittering agent. Lastly, the motorcraft cooling system additive is good for fast delivery and it runs the engine.

One customer says - "Use test strips (fleetguard coolant analysis test kit cc2602a) to check your coolant before you add. ". Most customers agree that the additive is good for reconditioning antifreeze.

• Now dyed yellow to eliminate engine coolant color change when mixing.
• New and hot releases.

Best For Reducing Engine Temp: Red Line Cooling System Additive

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Best part: Red Line Cooling System Additive costs comparatively low and it is available to ship in 24 hours. Make sure this fits by entering your model number. In addition, the additive reduces rust, corrosion and electrolysis, cleans and lubricates water pump seals. In short, with a 4.8 rating and more than 1544 buyers, the red line cooling systemadditive stands as the best choice.

Almost all customers quickly discovered that the additive makes a huge 30f difference in cooling, which is critical in the summers. In addition, they also found that the additive is great for reducing engine temp. To sum up, the tone of buyers is very positive and we believe that the additive suits the purpose.

• Blended with purified, deionized water and proper water percentage.
• Satisfies astm d2570 and astm d1384 corrosion tests for glycol-based antifreezes.
• Compatible with all antifreeze and coolants.
• Convenient, pre-mixed coolant for motorcycles, atvs, karts, etc.-pour and go.

Best With Great Stuff: Mishimoto Cooling System Additive

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Best part: Mishimoto Cooling System Additive costs comparatively low and it is available to ship in 24 hours. The mishimoto coolingsystem additive is compatible with all coolant types and does not require mixing. The manufacturer says: Keep up with Mishimoto and our mascot Chilly on all major social media channels to discover everything from new products, engineering blogs, deals and more. Also, it is 100% biodegradable, non-corrosive, and nontoxic, making it a safe and effective solution for reducing high coolant temperatures.

Finally, the mishimoto cooling system additive has produced a line of upgrades to fit nearly any application.

Almost all customers opine that the additive makes quality products and it shows with this great additive. Further, a few strongly agree that the additive does not work as well as far as cooling goes, fifty percent anti and water works better, for cooling and heating.

• Net weight: 4 fl oz. / note: non-corrosive, 100% recyclable.
• Formulated to prevent future corrosion and reduce existing build-up.
• decreases high coolant temperatures and does not require mixing.

Best With All Types: Bars Leaks Cooling System Additive

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The bar leak cooling system additive is suitable and reliable and fits well with your daily use. The bars leak cooling system additive is not sealed in 20 minutes, a second application may be required or mechanical repair may be needed. The Manufacturer says: Each individual bar’s leaks product is formulated and manufactured right here in the U.S.A. We’re committed to creating fast and affordable products that fit perfectly into your lifestyle and budget. This product is designed to be left in the cooling system to protect it from future leaks and overheating.

Most importantly, the bars leak coolingsystem additive reduced coolant temperature, antifreeze loss and no leaks or overheating.

Most customers agree that the additive came in with a leaking water pump on a '03 pt cruiser. Further, they say that the additive is a great option that works very well. Also, a few also found that the additive is easy to use ...working very well. With no doubts, this product passed the test and had very satisfied buyers eager to share their experience.

• Item package dimensions: 7.4 l x 3.9 w x 8.9 h (inches).
• This is great for pluging leaks.
• This is designed to worth every penny and it has included components.
• Manufacturer says: we recommend you drive the vehicle for 15 minutes.

Compatible With Water: Design Engineering Cooling System Additive

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If you often find yourself confused about appropriate and satisfactory additive,s Design Engineering Cooling System Additives should be your first option for buying. The design engineering cooling systemadditive reduces pre-existing scale build-up and it is also formulated with a corrosion inhibitor that reduces mineral deposits. Manufacturer says: We work with these customers to define their problem, determine the correct materials necessary to handle their heat or sound control issues and work to design a solution. Further, it is safe with all alloys and it is compatible with water.

Most importantly, the design engineering cooling system additive is the first additive that maintains ph levels that otherwise fluctuate over time, resulting in core damage.

Almost all customers opine that the additive has also shortened the run times of the furnace. In addition, they say that the additive will decompose in 21 days & have no environmental hazards. Further, a few strongly agree that the additive has anti corrosion additives plus reduces the engine temperdure. In short, at the price, they believe that they got a steal of a deal with it.

• Formulated with a corrosion inhibitor and reduces pre-existing scale build-up.
• Safe with all alloys - 100% biodegradable, non-corrosive and non-toxic additive.
• Manufacturer says: but there's another facet of our business that we specialize in.
• This design is tested and approved by the customer, production begins based on their requirements.

Best Coolant: Evans Cooling System Additive

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The Evans Cooling System Additive is capable of outshining several other additives featured in this list in overall features for the price point. The evans cooling system additive is especially effective in severe-duty applications where water-based coolants are challenged. Evans ' heavy duty coolant defends against heat-related damage while allowing the engine to continue producing its peak horsepower. Also, the additive has a high boiling point of 375 degrees f and provides low temperature protection too.

Above all, the evans cooling system additive recommended that the system be flushed with evans prep fluid, ec42001, prior to installing any waterless coolant.

"This will save your engine great stuff. " - says, one customer. In conclusion, most buyers found the additive is functionally comfortable and no one questions it.

• This reduces maintenance costs and it is very corrosive and a good conductor of electricity.
• This is above that limit, the coolant will perform no better than water-based antifreeze.
• Good brand reputation.