Preventive maintenance: Car liquids you need to change regularly

Everyone knows one needs to put fuel in a car to make it go. However, a vehicle also uses a number of other oils and lubricants to function, which need to be changed after a given time. Here is a quick and short guide on some of those items, what they do and when to change them.

Engine oil

An engine contains a lot of moving parts. And as the laws of physics state, when there's movement, there's friction. And where's fiction, there's heat. It is the job of engine oil to reduce friction by lubricating the moving parts as well as serving as a conductor for the built-up heat. In short, engine oil prolongs the life of the car's engine and makes sure it runs smoothly. 

But, like all good things, it doesn't last forever. The oil loses its effectiveness over time and requires to be changed after a certain period of use. The general rule of thumb is to change the oil every 10,000 to 15,000 km or every one or two years depending on how often the car is driven.

When changing the oil, make sure to use the recommended engine oil. Local mechanics in Bangladesh tend to use the wrong type of oil (ie 20w-30 in place of 5w-30), which is much thicker and might damage the engine in the long run. Check the car's user manual and/or engine bay to find the recommended oil for your car and make sure to use oil from a reputable brand, such as one recommended by the automaker itself.  

Coolant 

While engine oil keeps the inside of the engine cool, it's the job of cooling the engine block itself is handled by the car's coolant. 

Liquid coolant runs through a "jacket" surrounding the engine block, taking away the heat from the engine and dissipating it through the radiator. Much like oil, coolant degrades from overuse, though it lasts a lot longer.

It is generally recommended to put in fresh coolant every 48,000 to 50,000 km. Much like oil, it is best to use products recommended by the manufacturers, although do keep in mind most coolants need to be diluted with distilled water to a 50:50/60:40 ratio. 

Consult the user manual for the correct ratio or if it is available, buy the OEM (Original Equipment Manufacturer) premix to save yourself the trouble. 

Transmission/Gear oil

Auto manufacturers like to claim the oil inside the gearbox is good for the lifetime of the car. And while they are technically correct, their definition of "lifetime" vastly differs from yours and mine. Automakers typically count the life cycle of a car model to be five years, after which the design will go through a refresh or will be entirely replaced by a newer model.  As such, it's best practice to swap the old gearbox oil after five years, but with the major caveats. 

A gearbox is much more sensitive to oil than your engine. Most engines can run on incorrect oil to a reasonable margin, but putting the wrong oil inside the gearbox is a recipe for disaster. Furthermore, since automakers didn't intend for users to change gears oil, changing it requires trained professionals and a controlled environment. As such it is best practice to take the car to an official dealership to perform such maintenance.

Brake fluid 

Cars of the olden days used metal wires to accurate their brakes. Modern brake systems run on hydraulics, which uses fluid pressure instead. Unlike metal, liquids are not compressible, making them ideal for long term use. 

Brake fluids are not meant to be changed regularly, but the pipes containing them hold the risk of springing a leak, cracking or just falling apart after a long time of use. As such, it is recommended to check the brake lines during every oil change. 

Besides the pipes, most cars will have a brake fluid reservoir in the engine bay, with a clear "full-line" icon etched on it. If the liquid inside the reservoir is below the full line, top it off. Furthermore, Brake fluid is usually a light, clear colour. If it's not clean or transparent, then your brake fluid is dirty and needs changing.

Power steering fluid 

Anyone who ever had to drive a non-power steering car in the busy streets of Dhaka will know what a godsend modern power steering is. 

Power steering uses hydraulics to speed up the turning speed of the steering wheel, turning a motion that previously took two hands into a one-finger affair. The loss of said fluid will bring back those nightmares, so it is in our best interest to keep it full. 

Fortunately, power steering fluid usually lasts a long time, with the numbers suggesting well excess of 1,00,000km. But much like brake fluids, its plumbing might spring a leak from time to time, so it is best practice to check the tank every time you service your car. If it's below the recommended level, fill it up. If it keeps going down, consult a mechanic.      

Washer fluid

Although not as mechanically sensitive as other items on the list, washer fluid is essential to maintain a clear view through the windshield. A clean windshield is required for retaining maximum visibility on the road, as bad visibility endangers both you and everyone else on the road. 

Finding out when to fill up washer fluid is pretty self-explanatory, just fill it up when the jet stops squirting. Any mixture of water and soap will do the trick, but if you don't want dry soap stains on your glass, you might consider a purpose-built cleaning solution.