What are the effects of not changing the coolant on a car?

[CeciliaLynn]

Not changing the coolant has an impact on the car, which can prevent the engine from dissipating heat normally, leading to overheating of the engine. In severe cases, it may cause engine damage. The role of coolant: Coolant is a liquid containing special additives, mainly used in liquid-cooled engine cooling systems. It has excellent properties such as preventing freezing in winter, boiling in summer, and protecting against scale and corrosion throughout the year. Can different coolants be mixed? It is necessary to use the same brand of coolant. Different brands of coolant may have different production formulas. If mixed, various additives may react chemically, causing the additives to become ineffective. How to choose coolant: The basic indicators of coolant are the freezing point and boiling point. On the market, coolants have freezing points of -15℃, -25℃, -30℃, -40℃, etc. Generally, it is advisable to choose a coolant with a freezing point at least 10℃ lower than the lowest temperature in your region.

[Maria]

I've seen many cars develop issues due to prolonged neglect of coolant replacement. Coolant isn't just for freeze protection – its crucial role is engine cooling. After 3-5 years of use, the corrosion inhibitors deplete, allowing gradual rust formation in water passages and cooling systems. A completely rust-clogged radiator is even more alarming – I once repaired a vehicle with pipes entirely caked in iron oxide. The most dangerous consequence is lowered boiling point, which leads to overheating and potential engine block damage. Water pump seals also corrode and leak – I've frequently seen expansion tanks filled with brown sludge. Therefore, I recommend inspection/replacement at maximum 2-year or 40,000-km intervals.

[Barrett]

Veteran drivers tell you, this is not something to skimp on. I used to be stingy and didn't change it for five years, only to find the heater wasn't working in winter—turns out the coolant had deteriorated and clogged the heater core. Summer was even scarier, with the temperature gauge constantly hitting the red line. The mechanic pulled out a rusty thermostat and just shook his head. The radiator was so full of rust and sediment it looked like a mud pit, impossible to clean, and I ended up spending a fortune to replace the entire cooling system. The additives in the coolant had expired and lost effectiveness, corroding the aluminum cylinder head and heater pipes until they were full of holes. Now I follow the maintenance manual strictly—the money saved on repairs could cover a decade's worth of coolant changes.

[DiCharlie]

A lesson learned the hard way! Last winter, my car's heater suddenly stopped blowing hot air. The repair shop said the antifreeze hadn't been changed in six or seven years, and the rust particles had completely clogged the small heater core. It took three days to dismantle the dashboard for repairs, and the bill was painful to look at. The technician said those reddish-brown flocculent substances were corroded metal fragments and should have been replaced long ago. Deteriorated antifreeze can also cause rubber hoses to harden and crack—I even had greenish water stains leaking from my radiator hose. Now, whenever the seasons change, I unscrew the radiator cap to check. If the liquid looks cloudy or the level has dropped, I get nervous.

[VonLyla]

Auto repair shops dread customers who try to save small money like this. For vehicles with expired coolant, it typically costs 800 yuan just to flush the cooling system first - otherwise the new fluid will clump when added. Cast iron engines rust easily, while aluminum cylinder heads corrode and leak. I've handled cases where corroded cylinder heads needed major repairs after developing holes. Even worse is when water pump impellers get worn smooth by scale deposits, cutting cooling efficiency in half. The sludge buildup inside radiators resembles kettle limescale, requiring three hours of specialized cleaner circulation to remove. In the end, the combined flush + fluid replacement costs over triple regular maintenance while wasting far more time.

[BrodyLee]

Driving in the north requires extra attention to this. During last year's cold wave, some car owners had been using the same antifreeze for seven years, which ended up freezing into solid ice. Not only did the heater core freeze and crack, causing leaks, but the entire cooling system's pipes also expanded and ruptured. During repairs, it was found that the radiator cap was covered in green crystals, and in extreme cases, the engine block cracked from freezing. Our club tested old antifreeze and found that its freezing point could skyrocket to -5°C, causing it to freeze. Normally, the radiator cap would often emit a rusty-smelling foam, and the electric fan would frequently activate, draining the battery quickly. Now, before winter sets in, I always test the freezing point concentration and replace the fluid immediately if it appears cloudy.