A car is a complex mechanism consisting of thousands of rubbing parts, and the life of each of them directly depends on the quality of the lubricant. Many car owners mistakenly believe that maintenance is limited to regular engine oil changes, forgetting about other critical components. In fact, in a modern vehicle there are several types of technical fluids, each of which performs a unique function and requires timely replacement.
Ignoring transmission or hydraulic maintenance regulations can lead to expensive repairs, which often exceed the cost of multiple preventive maintenance. Oil fasting or loss of fluid properties leads to overheating, increased wear and, ultimately, complete failure of the unit. In this article we will analyze in detail which oils and liquids need to be replaced, how often this should be done and what to look for when choosing consumables.
Understanding that what oils need to be changed in your specific car will not only extend the life of the equipment, but also maintain confidence in safety on the road. You should not rely solely on manufacturers’ assurances about “maintenance-free” components, since the realities of operation often make adjustments to the factory recommendations.
Motor oil: the heart of your engine
The internal combustion engine is the main consumer of lubricants, and the quality of operation of this system determines the service life of the entire vehicle. Motor oil performs many functions: it lubricates rubbing vapors, removes heat, cleans parts from carbon deposits and protects metal from corrosion. Over time, the base base degrades and the additive package is produced, which leads to a loss of viscosity and protective properties.
Change intervals depend on many factors, including engine type, driving style and operating conditions. For modern synthetic oils, a mileage of 10 to 15 thousand kilometers is considered standard, however, in city traffic jams or frequent short trips, this interval must be reduced. Diesel engines with particulate filters require the use of low-ash oils with Low SAPS approval, so as not to clog the expensive filter with solid particles.
When choosing a product, it is important to pay attention not only to SAE viscosity, but also to the tolerances of a particular automaker. Using the wrong fluid may cause the seals to pop out or oil deposits to form on the pistons.
⚠️ Attention: Never mix oils from different manufacturers and chemical bases unless absolutely necessary. Emergency topping up is possible, but at the first opportunity the mixture must be completely replaced, since a chemical reaction between different additive packages can lead to sedimentation.
The oil level should be checked regularly, preferably on a warm engine after a short stop. A sharp drop in level may indicate leaks or oil loss through the piston rings, which requires immediate diagnosis.
Transmission oils: manual transmission, automatic transmission and CVTs
The transmission experiences enormous loads, transmitting torque from the engine to the wheels, and requires specific lubricants. In manual transmissions (Manual transmission) the oil operates under conditions of high pressure and temperature, protecting gears from scuffing. Here replacement is usually done less often than in the engine, but it should not be neglected, especially if you hear a hum or feel difficulty shifting gears.
Automatic transmissions (Automatic transmission) and variators (CVT) are much more sensitive systems. In them, oil acts not only as a lubricant, but also as a hydraulic working fluid that transmits force. Wear productsaccumulated in the ATF fluid can clog the valve body and solenoids, which will lead to kicks when switching and eventual breakdown of the box.
There is a myth that the automatic transmission is filled with oil for the entire service life of the car. In practice, by “service life,” manufacturers often mean a warranty period or 150-200 thousand kilometers, after which the gearbox may require major repairs. To maintain the health of the transmission, it is recommended to partially or completely replace the fluid every 60 thousand kilometers.
Why do CVTs require special attention?
CVTs operate by friction of metal belts on cones, and the slightest change in the properties of the oil (loss of frictional properties) leads to slippage and rapid wear of an expensive chain or belt.
When replacing, it is important to strictly use the specification specified in the manual. For some boxes ZF or Jatco the tolerances are so narrow that using an analogue can lead to unstable operation of the torque converter.
Steering hydraulics (power steering)
Power steering makes driving easy and comfortable, especially at low speeds and when parking. The working fluid in this system is a special oil that circulates under high pressure. Over time, wear products from the pump and rack, as well as moisture entering through the seals, accumulate in the liquid.
Darkening of the oil and the appearance of metal shavings in it is a sure sign of wear on the power steering pump. If you ignore these symptoms, the pump will begin to hum and then jam, leaving the driver without a booster at the most inopportune moment. Replacing the fluid and filter (if provided by the design) helps extend the life of the system.
The most commonly used liquid ATF red or special yellow or green hydraulic oils that cannot be mixed with each other.
☑️ Diagnostics of the power steering system
The replacement procedure often involves forcing old fluid through the system by rotating the steering wheel while the engine is running, which allows you to displace as much waste as possible from the lines and rack.
SUV axles and transfer cases
For owners of all-wheel drive vehicles, the issue of gearbox maintenance is especially acute. The final drive and transfer case use hypoid gears that experience extreme shear loads. Hypoid oil contains special extreme pressure additives (usually based on sulfur and phosphorus) that create a protective film on the gear teeth.
Water is the main enemy of gearboxes. When overcoming fords or deep snow, water can get inside through the breathers, turning the oil into an emulsion that is unable to lubricate parts. Regularly changing the oil in axles (usually every 40-60 thousand km) allows you to remove accumulated moisture and restore the protective properties of the lubricant.
Particular attention should be paid to gearboxes with interlocks. Such units often require oil with additional additives to protect the friction discs of the blocker. Using a conventional transmission can lead to slipping or, conversely, to “sticking” of the lock.
| Car assembly | Typical replacement interval | Key Feature | Consequences of ignoring |
|---|---|---|---|
| Engine | 10,000 – 15,000 km | Viscosity and base number | Seizure of liners, coking |
| Automatic / CVT | 40,000 – 60,000 km | Friction properties | Jerking, hydraulic unit failure |
| Manual transmission | 60,000 – 90,000 km | Wear protection (EP) | Noise, difficult switching |
| Gearboxes (bridges) | 40,000 – 60,000 km | Hypoid additives | Gear teeth destruction |
After active off-road driving, check the axle breathers for contamination. Dirt in the breather creates excess pressure when heated, squeezing oil through the seals.
Brake fluid: a safety issue
Although technically it is not an oil but a hydraulic fluid, its role in vehicle maintenance is critical. The brake system operates under conditions of high temperatures that arise when the pads rub against the discs. The main feature of brake fluid (DOT-4, DOT-5.1) - its hygroscopicity, that is, the ability to absorb moisture from the air.
The accumulation of water in brake fluid lowers its boiling point. During intense braking, the liquid can boil, forming gas plugs, which, unlike the liquid, are compressed. This leads to the effect of a “cotton” pedal and complete failure of the brakes at the most crucial moment.
Routine replacement of brake fluid is carried out every 2 years or every 40-60 thousand kilometers, regardless of mileage, since the aging process continues even when the car is idle. Before purchasing, check the condition of the liquid with a tester that measures the percentage of water content.
⚠️ Attention: Brake fluid is aggressive to paintwork and plastic. If it gets on the body or interior parts, wash it off immediately with plenty of water, otherwise the paint may swell and peel off.
The replacement process requires bleeding the system to remove air bubbles. It is best to entrust this procedure to professionals or use a specialized vacuum bleeding tool to ensure that there is no air in the lines.
Lubricants for suspension and joints
Although there are no closed volumes of oil in the suspension, many components require regular injection of grease. Constant velocity joints (CV joints), driveshafts, some types of ball joints and steering ends have boots that contain lubricant.
If the boot is damaged, the lubricant is washed out with water and mixed with dirt, turning into an abrasive paste. This leads to rapid destruction of the hinge. Regular inspection of the boots and replacement of lubricant if they are damaged is the key to a long life of the chassis.
Different types of lubricants are used for different components: lithium (for bearings), molybdenum (for CV joints experiencing shock loads) and calcium (for units in contact with water). Using the wrong lubricant may cause it to leak or lose its properties.
Regular replacement of technical fluids is 10-15 times cheaper than major repairs of the units they serve.
In modern cars, many components are considered maintenance-free and do not have syringes, but experienced craftsmen often drill holes for lubrication to extend the life of expensive suspension parts.
Is it possible to mix oils of different viscosities when topping up?
You can mix it for a short time if the oil level is critically low and you need to go to a service center. However, different base stocks and additive packages may react. After such topping up, it is advisable to completely replace the oil and filter as soon as possible.
How do you know when it’s time to change the gearbox oil?
The main signs: a change in color to dark or black, the appearance of a burning smell, the presence of metal shavings on the probe (if any) or a magnetic plug, as well as a change in the nature of the box operation (kicks, noise, difficult switching).
Do I need to flush the engine before changing the oil?
If you use quality oil and maintain drain intervals, flushing is usually not necessary. Modern oils contain detergent additives. Flushing is only necessary when switching to another type of oil or if there was obvious overheating and sludge formation in the engine.