Car antifreeze: the ultimate guide to prevent 80% of temperature-related breakdowns… and the hidden factor that damages new engines

What Is antifreeze and why your engine depends on it?

Think of it as your car’s circulatory system. Car antifreeze is a blend of demineralized water, glycols, and additives that:

• Doesn’t freeze until –35 °C, preventing engine block cracks.
• Doesn’t boil until around 135 °C, avoiding overheating in hills or summer traffic.
• Lubricates and protects metals, seals, and the water pump from corrosion and cavitation.

Without this fluid, any long drive turns into Russian roulette for your engine.

How it works in three simple steps

1. Glycol (ethylene or propylene glycol) modifies freezing and boiling points.
2. Anti-corrosion additives create a microscopic film that blocks rust and mineral deposits.
3. High-purity water optimizes heat transfer: 50% water + 50% glycol is the most efficient mix.

Pro tip: Modern formulas also include anti-foaming agents to avoid bubbles that reduce radiator efficiency.

Types, standards, and colors (why “green” is no longer enough)

*Color is only a guide. Two visually identical products can be chemically incompatible.

How to choose the right antifreeze (pro checklist)

• Read the manual: Look for VW G12++, BMW LL-04, Ford WSS-M97B44-D or equivalent.
• Consider your climate:
  • Cold region (< –15 °C): requires –35 °C protection.
  • Mild region: –18 °C is enough, but extra margin is smart.
• Don’t mix types: Mixing OAT and IAT forms gelatinous sludge that clogs radiator micro-channels.
• Check the spec sheet: Density at 20 °C (~1.065 kg/L)- Alkaline reserve (pH 7.5–8.5) are signs of quality

Clear signs it’s time to change it

• The fluid is no longer transparent and smells metallic.
• The temperature warning light rises faster than usual.
• Sediment or rust is visible in the expansion tank.
• It's been 5 years or 150,000 km since the last change.

Golden rule: When in doubt, draw a sample with a syringe and test it with a hydrometer. It costs less than a cup of coffee.

Three-minute annual maintenance plan

Following this mini-plan cuts the risk of sudden overheating by 70%.

Step-by-step replacement (easy and safe DIY)

Important: Always work with a cold engine and nitrile gloves.

• Drain
  • Lift the car and place a closed container (min. 5 L).
  • Loosen the radiator’s bottom valve and the expansion tank cap.
• Flush
  • Close valve, fill with distilled water, run engine 5 min, and drain again.
  • Repeat if the liquid comes out dirty.
• Refill
  • Mix concentrated antifreeze 50/50 as specified.
  • Pour slowly to max level.
• Bleed
  • Start engine, rev to 2,000 rpm, open bleed screw until fluid flows bubble-free.
  • Adjust final level.
• Recycle
  • Take used fluid to a hazardous waste facility. It's toxic and illegal to dump at home.

Total time: 45–60 min if it’s your first time.

Common mistakes mechanics daily see

Myths that confuse even veteran drivers

• “I only need antifreeze in winter.”
  False. Summer overheating kills more engines than freezing.
• “If it’s pink, it’s fine.”
  False. OAT and Si-OAT can look alike but have incompatible additives.
• “I’ll change it when it runs out.”
  False. Glycol degrades before it evaporates; if it's low, it may already be too late.

Quick FAQ (fast answers, fast actions)

Can I use propylene glycol instead of ethylene glycol?

Yes, it’s less toxic—ideal for EVs and eco zones—with similar thermal protection.

How much pressure should the radiator cap hold?

Between 0.9 and 1.4 bar, depending on the model. A weak cap lowers the real boiling point.

How do I know if there’s a leak?

Forget visible puddles—look for sweet white mist from the exhaust (oil and water mixed).

The Hidden Factor (The Closed Loop)

Each time you “top off” with water as a stopgap, you dilute the mix and rob your engine of protection. After four such top-ups, the freeze resistance can drop from –35 °C to –12 °C—without you noticing, because the color stays the same.

Pro solution: Record every top-up. If you’ve added more than a liter in total, schedule a full change or test with a hydrometer before winter.

Car antifreeze isn’t just a bright-colored fluid—it’s thermal insurance, a lubricant, and a corrosion inhibitor, all in one bottle. Choose the standard your carmaker requires, check concentration each fall, and change it by mileage or every 5 years. This routine will help you avoid breakdowns that easily exceed €1,000—and extend your engine’s lifespan by many more kilometers. "Now you have the professional—yet simple—guide to keep your car at the perfect temperature all year round."

Relying on domestic manufacturers such as Olipes and Proquisur ensures access to technically sound products, compliant with regulations, and backed by robust post-sale support. Both companies—members of the Autoparts From Spain initiative—are benchmarks in Spanish technical fluid formulation and active players in consolidating the global leadership of the Spanish automotive supply industry.

For any industry professional—be it distributor, technician, mechanic, or fleet manager—choosing a high-performance antifreeze isn’t a minor decision. It’s a direct investment in mechanical reliability, thermal efficiency, and operational sustainability.