Engine oil lubricates the moving parts of an engine, carries heat away from them, and holds contaminants until the filter traps them. It breaks down with use, which is why manufacturers set both a service interval and a minimum level.

Changing it at home is a manageable job for most drivers who have the right tools and a safe place to work. This guide covers when oil needs attention, how to change it step by step, and the mistakes that cause the most damage.

Quick Facts

• Check your engine oil at least once a month.
• Always use the oil grade specified in your owner's manual.
• Stop-start driving and heavy traffic can shorten oil life.
• Never work under a vehicle supported only by a jack.
• Dispose of used oil responsibly.
• Keeping up with maintenance can help reduce the risk of breakdowns.

How to change oil: Step by step

The steps are much the same on most cars. Here’s what you should know.

Knowing when to top up or change the oil

Check the level about once a month. With the car on level ground and the engine off, pull the dipstick out, wipe it, reinsert it fully, and read the oil against the minimum and maximum marks. Signs that the oil needs attention include:

• An oil pressure or oil change warning light
• A level at or below the minimum mark
• Oil that looks dark and thick or feels gritty rather than smooth
• Knocking or ticking from the engine

Manuals also set an interval. Conventional oil is typically changed every 8,000 to 12,000 km, and full synthetic usually lasts longer, though the figure for your car may vary. Drivers who cover little distance are generally still advised to change it once a year.

Gathering the tools and materials

Have everything ready before you start:

• Oil of the grade and quantity stated in the manual
• New oil filter for your exact model
• New drain plug washer, if your car uses one
• Socket or spanner and an oil filter wrench
• Drain pan and a funnel
• Ramps or axle stands, and wheel chocks
• Gloves, rags and a sealed container for the old oil

Preparing the vehicle

Park on level ground and apply the handbrake. Running the engine for a few minutes helps the oil flow out, though it needs to cool afterwards so the sump and exhaust are safe to touch. If clearance is too low to reach the sump, use ramps or raise the car and support it on axle stands rated for its weight. Never work under a vehicle held by a jack alone.

Draining the old oil

Put the drain pan under the sump plug, loosen the plug with a socket, and unthread the last turns by hand. Let the oil drain fully, which usually takes several minutes. Wipe the plug and its sealing face, fit a new washer if one is used, then refit the plug and tighten it to the figure given in the manual. Overtightening strips the threads in the sump.

Replacing the oil filter

Move the pan under the filter, which still holds oil. Spin-on filters unscrew anticlockwise with a filter wrench. Check that the old rubber gasket came away with the filter, because a second gasket left on the housing can let go and empty the sump. Wipe the mounting face, smear fresh oil around the new gasket, fit the filter by hand until it meets the face, then tighten it by the amount printed on the filter or its packaging. Cartridge filters take a new element and new O-rings instead.

Refilling and checking the level

Lower the car, remove the filler cap, and pour in slightly less than the stated capacity through a funnel. Check the dipstick and add oil gradually until the level sits between the marks, then refit the cap. Start the engine, let it idle for a minute, and look underneath for drips at the plug and filter. Switch off, wait a few minutes, and check the level again. Reset the oil life monitor if the car has one.

Changing oil: Key tips and best practices

Here are key tips to keep in mind.

Use the oil your manual specifies

Viscosity grades such as 5W-30 are chosen for the clearances and oil passages inside a particular engine, and a different grade changes how well the oil protects it. Quantity matters as much as grade. Too little oil raises friction and heat, while too much can foam and put pressure on seals and gaskets.

Tighten to the specified figure, not as hard as you can

Many sumps are aluminium and strip easily, and an overtightened filter is difficult to remove at the next change. A torque wrench and the manual's figures remove the guesswork. Without one, tighten until the plug feels snug and add no more than a small further turn.

Dispose of used oil and filters properly

Used oil is a contaminant, and pouring it into a drain, a gully, or onto open ground pollutes soil and water. Keep it in a sealed container along with the old filter and take both to a garage, service station, or waste handler that accepts them. Call ahead, as not every workshop takes oil from the public.

Keep a record and adjust for your driving

Note the date and the odometer reading each time so the next change is not a guess. Stop-start traffic, frequent short journeys, and dusty or rough roads all shorten oil life, and manufacturers usually publish a shorter interval for conditions of that kind.

Drive with confidence

Regular maintenance, such as oil changes, helps protect your vehicle and gives you peace of mind on the road. When it comes to protecting your vehicle against the unexpected, the right insurance matters, too. General Accident offers a range of car insurance policies to help protect you and give you greater confidence behind the wheel.

Get a quick quote today.