Selecting the proper motor oil and transmission fluid is critical to keeping your vehicle running smoothly for years to come. However, with so many options on the market, choosing the right oils for your make and model can seem daunting. This guide breaks down the key facts you need to know about engine oils and gearbox fluids to make informed decisions when maintaining your motor.
Motor Oils: Types and Viscosity Ratings
Motor oil primarily functions to lubricate the engine by reducing friction and preventing wear. It also plays a vital role in cleaning, cooling, and sealing the engine. The oil type and viscosity you choose depends on your vehicle’s specific requirements.
Conventional and Synthetic Oils
Conventional motor oils are refined from crude oil and enhanced with additives. Synthetic oils are chemically engineered in a laboratory setting. Synthetics generally provide improved low-temperature flow, resistance to oxidation, and oil film strength. They allow for longer drain intervals compared to conventional oils.
Single or Multi-Grade Oils
Single-grade oils are straight viscosity oils that list a single number like 10W or 20W. The number refers to the viscosity grade at operating temperature.
Multi-grade oils flow well in cold temperatures but also maintain viscosity in hot conditions. They have two numbers like 5W-30. The first number is the viscosity grade at low temperature, and the second refers to high-temperature viscosity.
High Mileage Oils
Once an engine passes about 75,000 miles, switching to a high mileage oil can help reduce leaks and oil consumption in older, worn engines. These oils have extra seal conditioners and additives that can rejuvenate ageing seals and gaskets.
Viscosity Ratings
Viscosity refers to an oil’s resistance to flow. The proper viscosity grade for your vehicle ensures the oil can flow quickly to lubricate parts when the engine starts but also maintains a thick enough layer of protection at running temperature. Check your owner’s manual for the recommended viscosity.
Transmission Fluids: Types and Functions
Like motor oil, transmission fluid plays a number of critical roles within your gearbox. It lubricates moving parts, regulates temperature, and keeps components clean. The specific fluid your transmission requires depends on the type.
Automatic Transmission Fluid (ATF)
ATF lubricates and cools automatic gearboxes. Most modern automatic transmissions use some variation of ATF but check your owner’s manual for the exact type required as formulations can differ between manufacturers.
Manual Transmission Fluid
Manual transmissions use gear oil rather than ATF. It has additives tailored for the synchronisers, bearings, and gears in manual gearboxes. You’ll need to top up the oil as these transmissions lack a self-contained fluid reservoir.
Continuously Variable Transmission (CVT) Fluid
Unlike manual and automatic transmissions, CVTs have pulleys and belts rather than gears. CVT fluid has high-temperature viscosity and specific frictional properties to prevent belt slippage. Always use the factory CVT fluid specified for your vehicle.
For example, using the right transmission fluid for Audi A4 is crucial for smooth gear changes, optimal performance and extended transmission system life, but it’s worth remembering that Audi vehicles require specific types of fluids to meet their exacting standards.
How Much Oil to Use
If you want to know how much oil does my car need – autodoc.co.uk has a good resource, but in general, the oil capacity you need varies by vehicle. Check your owner’s manual for the total quantity your engine requires when changing the oil and filter. Top up amounts differ as well if your oil is low between changes. Most cars take 4-6 litres in total. When in doubt, your local mechanic can look up the factory oil capacity for your make and model.
Best Practices for Oil Changes
Follow your recommended oil change intervals to prevent excessive engine wear. Severe driving conditions like frequent towing, extensive idling, and stop-and-go traffic may require more frequent changes.
Here are some tips for successful DIY oil changes:
- Allow the engine to warm up before draining old oil for faster drainage.
- Compare the colour of the old and new oil to check the condition.
- Tighten the drain plug and replace the oil filter securely to avoid leaks.
- Use a funnel when pouring in new oil and pause to check the dipstick level periodically to avoid overfilling.
Properly maintaining your car with the right oils leads to improved fuel economy, performance, and engine longevity. With some basic knowledge about motor and transmission fluids, you can make informed choices when selecting lubricants for your vehicle.
