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How to Check Your Engine Oil & Signs Your Oil Needs Changing
Your car engine relies on engine oil to lubricate and protect all its moving parts. Clean engine oil helps prevent wear and corrosion, and slows down the buildup of dirt and harmful deposits inside your engine.
Regularly checking your oil and filter will improve your car's performance and extend the life of your engine. We’ll show you how to check your oil correctly and explain the common signs that your engine oil and filter need replacing.
What’s Included In This Article?
Tools You’ll Need
Before you check your engine oil, you’ll need to grab a few basic tools or items to help you with the job. We recommend getting:
A clean cloth or rag to wipe your dipstick clean before taking an oil reading
Gloves to keep your hands safe and clean
A torch if you’re checking your car oil in an area with limited visibility or lighting
How To Check Your Engine Oil
Step 1: Park your vehicle in a suitable place
Make sure your engine has had a chance to cool down properly to perform your oil check safely. Park your vehicle on even ground to get an accurate oil level reading.
Step 2: Lift your bonnet and locate your dipstick
Put on your gloves to keep your hands safe and clean. Release and lift your vehicle’s bonnet according to the instructions provided in your manual. Make sure your bonnet is secured and locate your oil dipstick. Again, you can refer to your vehicle manual if you're having trouble finding it.
Step 3: Remove and wipe the dipstick
Remove your dipstick slowly, making sure not to flick oil on yourself. Take your rag or cloth and wipe your dipstick clean, removing all of the oil so you can see the ‘minimum’ and ‘maximum’ measurement markers at the tip.
Step 4: Reinsert your dipstick and remove it once more
Place your clean dipstick into the correct insertion point. Make sure the dipstick is all the way in, wait 2 or 3 seconds, and carefully remove it (again).
Step 5: Read the oil level and note the oil condition
Check your dipstick’s ‘minimum’ and ‘maximum’ measurement markers to see whether your oil levels are within the healthy range or if you need a top-up. Inspect the oil on the cloth after wiping it off the dipstick to check whether it’s amber and clean or dark and dirty.
Step 6: Change your oil and filter if needed
If your level is low or your oil is dark and dirty, it’s time to take action. Find out how to change your oil and oil filter.
How Often Should You Check Your Oil and Filter?
As an engine burns fuel, it degrades the oil within the engine. Regularly changing the oil in your engine helps to remove harmful contaminates and replenishes additives which have been depleted over time. You should change your oil according to your manufacturer’s recommendations, but you’ll usually need to do so every 5,000 miles or 6 months.
Most oil filters need to be replaced every 8,000 miles or once a year, but we recommend changing your oil and filter at the same time.
Signs It’s Time to Change Your Oil or Oil Filter
Your car will give you several warning signs that your oil and filter need replacing. Here’s what to watch for:
Oil warning lights showing up on your vehicle’s dashboard
Dark, dirty oil that’s sludgy or gritty
Excessive exhaust smoke
Loud engine noises like ticking, rumbling, or knocking
Reduced oil pressure
Sluggish acceleration and poor fuel efficiency
A low oil level
FAQs
Can a dirty oil filter damage my vehicle?
A clogged, worn, or dirty filter can restrict oil flow and circulate dirty oil back into your engine, wearing your vehicle’s components over time. A clogged filter and dirty oil can also cause your engine to overheat, affecting performance and reducing your vehicle’s lifespan. We recommend checking your oil every 1,000 to 2,000 miles or before every long-distance journey to make sure it’s clean and topped up to a healthy level.
Can I change the oil filter myself?
If you have the right tools and enough basic knowledge of vehicle maintenance, changing your oil filter and oil is a fairly straightforward job. We recommend changing your oil and filter at the same time to save time, prevent contamination, and improve engine performance.
What does the combination of numbers and letters on a bottle mean?
Every engine is designed to use a particular oil viscosity in order to lubricate the engine components properly. Using oil which is too thin can cause engine issues, while oil that’s too thick means the engine has to work harder, and so becomes less efficient.
The number rating for engine oil shows the SAE viscosity rating at different temperatures. For example, if your car uses 5W-30 oil;
The 5 is the viscosity rating when it is cold
the ‘W’ stands for Winter
30 is the viscosity rating when then engine is at operating temperature. This is usually around 100ºC (212ºF)
What’s engine oil made from?
Engine oils vary from manufacturer to manufacturer, but generally an engine oil will be made up of between 75-90% base oil. The remaining 10-25% is made up of additives which help to maintain the oil’s viscosity at high temperatures.
The base oil determines the fundamental properties of the engine oil and the additives help to enhance the base oil as well as helping to maintain the base oil and the engine components.
What’s the difference between conventional and synthetic engine oil?
The base oil within any engine oil is either conventional or synthetic. If the base oil is conventional, this means it has only been refined from crude oil. If the base oil is synthetic, it means that the oil has gone through an additional chemical engineering process. The additional process gives the oil better properties, such as more uniform oil molecules which create better lubrication, resulting in better engine performance.
Is synthetic oil compatible with conventional oil?
Engine oil labelled as synthetic already has conventional engine oil as part of its formulation, in the base oil. Manufacturers are also careful to test engine oils to make sure they are compatible with other brands. This means that as long as you use oils of the same SAE viscosity rating you can mix engine oils from different manufacturers.
However, we recommend sticking to one type and not mixing engine oils for the best results.
What’s engine sludge, and what causes it?
Every time you use your car’s engine, by-products from combustion build up and contaminate the engine’s oil. Over time the contaminants build up and can settle in the engine oil forming a ‘sludge’ in the bottom of the engine. Using low quality oils, not regularly changing your engine oil, or infrequent engine maintenance can all lead to sludge forming inside your engine.