Five Fluids You Should Check To Keep Your Car Running Smoothly


Cars need a lot of maintenance to keep running smoothly, and you can cover a good chunk of that by checking the fluids regularly. Here are the five fluids you should check on a regular basis.

A large portion of your car’s maintenance is preventative. Regardless of your skill level, anyone who can lift a bonnet can check the fluids. Doing so on a regular basis keeps your car running well and your repair costs down. Knowing the basics also empowers you: when you’re getting any maintenance on your car, you’re less likely to be swindled into flushing and replacing fluids unnecessarily.

All you need to know is where to look and what to look for. Keep in mind that every car is a little different, but the below dates should apply universally.

Engine Oil

The first thing you probably ever learnt about on your first car was how to check the engine oil. In most cars, you just need to pop up your bonnet, find the oil dipstick, pull it out and wipe it down. Repeat that again, and you’ll have your oil level. If it’s in the safe level, continue on your merry way. If it’s not, you need to add more. Depending on the age of the car, you may or may not need to add oil frequently. If your car burns through a lot of oil, it’s worth going to a mechanic.

How often to check it: It was once recommended that you check your oil every time you fill up, but it’s safe to check modern cars once a month.

How often to replace it: This depends on the car, manufacturer and year. The “5000km or every six months” saying doesn’t really apply any more. Instead, check your owner’s manual for the manufacturer’s recommendations on when to change your engine oil.

Transmission Fluid

Your transmission fluid is what keeps the gears on your car moving smoothly. You can check your transmission fluid the same way you check your engine oil, except the car should be running when you do it. Unlike your engine oil, transmission fluid is part of a closed system, so it should never be low. If it is, take it to a mechanic. Instead of volume, you’re looking at the quality of the fluid. The fluid should be red. If the fluid is brown or smells burnt, it’s time to replace it.

How often to check it: Monthly.

How often to replace it: This varies from car to car and depends on transmission type, but it’s typically between every 80,000km and 160,000km.


As the name implies, coolant, or antifreeze, keeps your car running cool. If you ever run low on coolant, your car is at risk of overheating. The coolant is inside you radiator, and you can check it by removing the radiator cap when the car is cool (never check it when it’s hot or your car is running) and looking inside. Once you remove the cap, you should see a line that indicates where the coolant should come up to. If it’s low, you can add more, but make sure you add the same type of coolant currently in the car.

How often to check it: Twice yearly.

How often to replace it: Every two to three years.

Brake Fluid

Just like the transmission fluid, your brake fluid is part of a closed system, so your car shouldn’t ever run out of it. However, it’s still worth checking to make sure it’s clean. Brake fluid keeps your brakes working properly, so if they ever feel a little off, checking your brake fluid is usually the first step. You can do this by checking the brake fluid reservoir on the driver side of your car. You can usually check the level just by looking at the outside of the container. The fluid should be a golden colour. If it’s brown, it’s time to replace it.

How often to check it: When you change your oil.

How often to replace it: Every two years.

Power Steering Fluid

Your power steering fluid helps keeps your steering smooth and easy. When the power steering fluid starts to get low, you might feel a “creaking” in the steering wheel or hear some weird sounds. To check it, all you need to do is pop the bonnet and find the reservoir. Usually, you can check it visually by looking at the reservoir. Power steering fluid doesn’t usually drop too much, so it’s worth taking your car into a mechanic or looking for a leak if it does get low.

How often to check it: Once a month.

How often to replace it: Between 80,000km and never. Typically speaking, most car manuals recommend keeping the power steering fluid levels topped off, but you’ll rarely need to flush and replace it. Double check your owner’s manual to make sure you can ignore yours.

So set up those calendar reminders and make those notes. If you’re checking your car’s fluids regularly, it will last a heck of a lot longer.


  • Not really a check but those with diesel engines should know what to do to get water out of the fuel system.

  • Engine Oil
    I know of some modern cars that it is still a good idea to check engine oil everytime you fill up (once a month does usually suffice though). Some manufacturers still consider 1 litre per thousand kilometres acceptable useage. That can equate to buring the oil capacity of the sump 3 to 4 times between services.

    I personally feel that using that much oil is too much but have had to argue the opposite to support a particular manufacturer.

    One other point is that you should check oil on a new car regularly. Often new cars burn oil during their wearing in stage. Often manufacturers won’t consider oil burn as engine wear until a reasonable amount of kilometres are done (for example 15,000km). A side note, often they won’t listen to complaint of excessive fuel useage for that amount of distance either.

    Transmission Fluid
    Often is is sooner than 80,000km. Many vehicles are 40,000km.

    Brake Fluid
    Reservoir’s are not always on the drivers side but are usually.
    Checking brake fluid visually without taking the lid off can be dangerous as they often have rubber inserts that move into the reservoir to keep the fluid level up as the fluid is either slowly lost or the brake pads/shoes wear out. I have seen cases of people complaining that their brake pedal goes to the floor and they have checked the fluid and it is fine however they are all but out of fluid but they don’t realise as they don’t remove the lid. When removing the lid, you need to remember that brake fluid will eat paint away and if any drops are spilt then your should immediately wash them away with water but take extreme caution to not get any water in the reservoir.

    Power Steering Fluid
    Some cars don’t have a recommend interval but it still requires replacing. I have seen some very filthy power steering fluid which can cause problems. Many manufacturers don’t give an interval but it should be checked during services and recommended as needing replacement when required.

  • “The coolant is inside you radiator, and you can check it by removing the radiator cap when the car is cool (never check it when it’s hot or your car is running) and looking inside.”

    Ummmm…. maybe I’m an idiot but don’t you check the reservoir, not the actual radiator?? You shouldn’t really have a need to touch the radiator cap.

    • Always a good idea to check both – identifies any issues with the hose that feeds the radiator.

    • Depends. Sometimes when there are issues the reservoir can appear full but the radiator can be low and cause overheating.

  • Gee I wouldn’t want to change the trans fluid on my diesel Mondeo every 40,000km…its around $400 to do that!!!

    • Sounds expensive. Must take some seriously expensive oil or is ridiculously complexed and costs a fortune in labour.

  • Tell me about it! One Ford dealer said $700 so I rang around and got it for $400 from another Ford place. Thought they would all be around the same price.
    Apparently a special tool is required that only Ford workshops have. The actual oil is $65 per litre as well. I’m sure other oil could be used but they sort of have me by the balls…

    • If I remember correctly the ZF autos used in Modeos are a sealed type and never supposed to be changed but is beneficial around the 150,000km mark. I’ve got a similar one in a Territory and the oil is roughly $65 per litre and not sure why it’s that expensive, but it is. IDK why they want $700 overall for the service though

      • I was hoping it would be of a sealed type but unfortunately its not and the service manual recommends it to be done around 60,000km. If your car runs out of warranty and the trans fluid hasn’t been replaced and the transmission packs up, apparently you have to wear it. I think if you’re out of warranty, you’d have to wear it all yourself anyway!

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