Every car, VW or otherwise, with an internal combustion engine requires six essential fluids.
They’re usually all things you can check yourself by opening the bonnet.
In this blog, we’ll walk you through what each of these essential fluids for your VW does, and why they’re important.
In your VW owner’s manual, you’ll find a list or a diagram that shows you where you can measure and top up each of these fluids, if applicable.
Engine oil
Your engine burns fuel. Naturally, this generates a lot of heat. As the moving metal components get hotter, they expand. This makes them rub against each other.
Engine oil coats the metal surfaces and acts as a lubricant. That means the metal parts don’t grind into each other.
Without engine oil, you’d quickly run into problems like poor performance, worse fuel economy and overheating. In severe cases, the engine may even seize.
You can check your engine oil level and condition using the dipstick, and top it up by opening the filler cap and pouring the correct engine oil in. Check your owner’s manual to find the right oil specification (VW followed by a ‘500.00’ number, for example, 504.00, 508.00, etc.).
Over time, oil breaks down, gets dirty, and forms sludge. At every service interval, your car should have its oil drained and replaced, along with the oil filter.
Coolant
Coolant does exactly what it says on the tin. It keeps your engine from overheating.
Coolant is essentially water mixed with antifreeze. It also contains additives to prevent freezing, corrosion and microbial growth. These additives are extremely poisonous, which is why coolant must never be ingested.
A pump sends this mixture of water and additives through small channels in the engine block. The water absorbs heat from the engine before passing through the radiator, where the heat is released into the air.
Check your coolant header tank, also known as the reservoir. The fluid level should be between MIN and MAX. Top it up with the coolant specified in your owner’s manual (usually G12, G12+, G12++, or G13).
Windscreen washer fluid
From bugs splatting on the windscreen to tree sap and pollen, windscreen washer fluid ensures you can see where you’re going.
Windscreen washer fluid is mainly made from water, alcohol (usually methanol or ethanol) and mild detergents that help remove dirt, insects and oily road film from the glass. The alcohol helps the fluid evaporate quickly and prevents it from freezing in cold temperatures, while the detergents break down grime so the wipers can clear it away.
Once again, these additives are highly toxic. Windscreen washer fluid should never be ingested.
You can top your windscreen washer fluid up by purchasing a bottle at the shop or the petrol station. Simply open the cap and pour it in until the reservoir is full.
Brake fluid
Brake fluid is a hydraulic fluid. It transfers the force from your brake pedal to the brakes at the wheels. When you press the pedal, the fluid moves through sealed lines and uses hydraulic pressure to push the brake pads against the discs, slowing the car down.
One of the biggest things to check with brake fluid is air bubbles. If there are any air bubbles in the system, the hydraulic system won’t work properly. This leads to a spongy feeling in the brakes. It’s why your mechanic should check and service your brakes on a semi-regular basis, and occasionally flush and refill the system.
You can top the brake fluid up yourself. Identify the brake reservoir and open the cap. Find the correct brake fluid in your owner’s manual (usually DOT 4 for Volkswagens). Ensure you use the correct type.
If you notice that the fluid was below the MIN mark on the header tank, air bubbles may have entered the system. You need to bleed the brakes. If you don’t know how to do this, bring your car to your trusted local VW service centre.
Power steering fluid
Before the 1990s, most cars didn’t have power steering. That meant turning the steering wheel, especially at low speeds or when parking, took a lot of effort. Power steering helps by amplifying the force you apply to the wheel, making the car much easier to steer.
Traditionally, power steering is a hydraulic system. That hydraulic system occasionally needs checking and topping up. To top up power steering fluid, first check your owner’s manual to confirm the correct fluid specification for your Volkswagen. Locate the power steering reservoir under the bonnet, check the level, and slowly add the correct fluid until it reaches the recommended mark without overfilling.
Your technician can drain and replace the power steering fluid if it becomes old or contaminated, for example, if it turns dark or gritty. They may flush the system and refill it with fresh fluid to help keep the steering pump, rack, and seals working.
However, most modern cars use electric power steering. That doesn’t require power steering fluid, or any kind of fluid at all. Instead, it uses an electric motor to assist the steering. If you notice any electric or hydraulic power steering problems, it’s best to leave these to an expert.
Gearbox oil/ATF
This is an essential fluid for your VW, but it’s the one that usually doesn’t require any input from you.
This fluid works in a similar way to engine oil, but it sits in your gearbox. The gearbox contains moving metal parts that mesh together, so lubrication is equally as important here. Because the shear forces and pressures are so much stronger in the gearbox, gearbox oil tends to be much thicker… and smellier!
In the UK, we usually use ‘gearbox oil’ to refer to the oil in manual gearboxes. ‘ATF’ stands for automatic transmission fluid, and it’s what you put into automatic gearboxes.
Most modern gearboxes are designed as ‘sealed for life’ systems, meaning you shouldn’t need to top up the fluid during normal ownership. If a technician discovers a leak, repairing it is usually a specialist job.
Some older automatic gearboxes may come with an ATF dipstick and filler cap. However, that’s rare these days.
A note about EVs
With more EVs on the road, it’s worth briefly touching on what fluids these vehicles require. Electric VWs still use brake fluid (VW EVs still use hydraulic braking systems) and windscreen washer fluid.
You don’t find hydraulic power steering in any modern VW EV, or any mainstream EV for that matter. These all come with electric power steering.
Although electric VWs still have a gearbox, it’s called a ‘single-speed reduction gearbox’. This is lubricated with a specialist gear oil, not ATF, and it typically isn’t something VW ever expects you to check or top up yourself.
EVs also use thermal management coolant to regulate the temperature of the battery, electric motor and power electronics. These components may use separate cooling circuits, but they all rely on dedicated coolant to keep temperatures within the safe operating range. Once again, these systems are sealed and should be inspected or serviced by only trained Volkswagen EV technicians.
And hybrids, of course, have all the same engine components as a regular petrol- or diesel-engined car – as well as EV-specific things like battery coolant.
Keep your car healthy with a service from Sunset VW
If you’re feeling overwhelmed with all the essential fluids under your VW’s bonnet, it’s okay. We’re here to help. As your local VW specialist garage in Derby, we have over 40 years of experience servicing Volkswagen cars. We know what to watch out for and how to keep your car running at peak performance and optimal fuel efficiency.
We’ll help you stay safe on the roads and maximise your car’s resale value. Give us a call today to book your VW in for a health check or service.