Think of your vehicle as a human body. Much like our body depends on blood, water, and other essential fluids to function efficiently, your car too needs a variety of fluids to operate optimally. Understanding the various automotive fluids and their functions can go a long way in ensuring your vehicle’s longevity and performance. 

In this part of our comprehensive guide, we’ll examine engine oil, transmission fluid, and coolant/antifreeze, detailing what they do and why they’re crucial to your car’s well-being. 

Engine Oil 

Just as your joints need synovial fluid to avoid friction and ensure smooth movement, your car’s engine relies on engine oil. Engine oil lubricates the myriad moving parts within the engine, minimizing friction and consequently reducing heat. This lubrication prevents wear and tear on the components, ensuring they operate smoothly and efficiently, thereby enhancing your car’s lifespan. 

Regular oil changes and checks are a must. Why, you ask? Over time, engine oil breaks down and can become contaminated with dust, dirt, and debris from the engine and the environment. This causes the oil to lose its viscosity (or “thickness”), compromising its lubricating properties. Most manufacturers recommend an oil change every 3,000 to 5,000 miles, but check your vehicle’s manual for specifics. And don’t forget to check your oil levels periodically – an engine running on low oil is a recipe for disaster. 

Transmission Fluid 

Next in line is transmission fluid. If engine oil is the lifeblood of your car’s engine, then transmission fluid is the circulatory system for your car’s transmission. Transmission fluid serves multiple purposes – it cools, lubricates, and transmits power from the engine to the transmission, which then drives the wheels. 

Maintaining the right levels of transmission fluid and regular fluid changes are as critical as engine oil maintenance. Over time, like engine oil, transmission fluid can degrade and become contaminated, leading to less efficient transmission operation, increased wear, and even transmission failure. Most car manufacturers recommend changing the transmission fluid every 30,000 to 60,000 miles, but your vehicle’s manual should have the most accurate information for your specific model. 


The last, but certainly not the least, is the coolant or antifreeze. Its role is as important and clear as its name implies – to keep your engine cool and prevent it from freezing in cold temperatures. As the engine runs, it generates heat. Coolant circulates through the engine and absorbs this heat, then carries it away to the radiator where it’s dissipated into the air, thus preventing the engine from overheating.  

Regular checks and fluid replacements are essential here too. Old or contaminated coolant can lead to ineffective cooling, potential overheating, and in severe cases, engine damage. A general rule of thumb is to check your coolant level at least twice a year – before summer and before winter – and to flush and replace the coolant approximately every 30,000 miles. 


In summary, understanding your car’s fluids – the engine oil, transmission fluid, and coolant – is fundamental to maintaining your car’s health and longevity. Regular checks, timely replacements, and understanding their functions can save you from unnecessary repairs and expenses. 


In Part 2 of our comprehensive guide, we’ll delve deeper and talk about other vital fluids such as brake fluid, power steering fluid, and windshield washer fluid. Stay tuned for a continuing deep dive under the hood of your vehicle.