How To Check Engine Oil Level In Your Car

As a general rule, it is best to check your oil when the engine is cold and the car is parked on a level surface. Checking when cold will give you a true idea of what the car’s oil levels are like. You want to know how much oil is in the sump. Checking when hot will give you an unrealistic reading, because some of the oil will be circulating around the engine, and the oil will be at a different temperature.

The markings on the dipstick are set based on the assumption that the oil levels in the sump will be measured when the car is cold and the engine is level. Too much oil is as bad as too little. If you get a low reading from a warm engine and top up your car, you could end up doing more harm than good by over-filling the oil.

You can top up oil by removing the oil filler cap, and slowly pouring a little oil into the hole, using a funnel. Add a little oil, give it a while to drain into the engine, and re-check your oil levels using the dipstick. Do this slowly and carefully, because over-filling the oil can cause leaks.

How to Check Your Engine Oil

Checking your oil is a simple job, and one that anyone can do without needing any special tools. All you need is a clean rag (to wipe the dipstick), some oil and a funnel, to top up the oil levels if required.

To check your oil:

  • Park your car on a level surface.
  • Switch off the engine and let it cool for a while.
  • The engine should have cooled off after about 5 minutes (wait longer if you have driven a long way or the engine is otherwise very hot).
  • Open your bonnet and locate the dipstick. Usually, this will be a brightly colored pole sticking out. Pull it out of the tube, and use a clean rag to wipe off the oil at the end of the stick.
  • Slowly push the dipstick back into the tube until it is fully sealed. On some vehicles you may find that it clicksin to position when inserted correctly. You then need to pull it back out again. Make a note of where the oil mark on the dipstick ends.
  • There should be two marks on the dipstick, one above the other. The oil level should be between those two marks. If it is closer to the lower mark than the upper one, or even below the lower one, then that means you don’t have enough oil in the engine, and you will need to top it up.

Checking Oil Quality

The oil used in automobiles should be of a specific consistency and quality. Oil that is impure can damage the engine, and oil that is too thin will not protect the engine well enough. For this reason, it is important to pay attention to the quality of the oil as well as the amount of oil in the sump.

The oil on your dipstick could be inky black, or light gold, or any colour in between depending on the brand of oil that you have been using in your car. You don’t need to worry too much about the colour of the oil, but the consistency is important. If you see some creamy-coloured deposits on the dipstick- something that looks a bit like mayonnaise, then this could be a sign that there is a serious problem with your engine. If possible, don’t drive the car after seeing that sort of contamination in your oil. Call a trusted garage and get them to have a look at it as soon as possible.

Engine oil will break down over time because of the stresses it is put under while you are driving. Good, working oil is smooth and glossy. It may be very dark, but it should have some transparency to it. If it is grainy or sludgy this could indicate that there are impurities in your oil or that the molecular strucure has started to break down. Either way it will need replacing. Oil that is thick to the point of being opaque is also old and needs changed. Another sign of bad oil is if it has a putrid smell to it.

Oil that is oxidized or contaminated will have no interfacial tension to it. This means that if you place a drop of the oil onto some water, it will spread out over the water, instead of forming a bead. If your oil does this, change it.

Another thing to look out for is coolant contamination. If you see brown bubbles or a crusty residue above the oil line on your dipstick, this is a sign that some cooling fluid has leaked into the engine. You may be able to smell antifreeze on the dipstick, and you may notice that your exhaust smoke has a sweet odour to it. If you think that you have a coolant leak, take your car in for a service immediately.

Monitoring your oil levels and knowing when to check engine oil level is one of the simplest but most important parts of car maintenance. If you keep your oil (and other fluids) well topped up, and make sure that your battery is always charged and your spark plugs are clean and in good working order, this will help to prevent the vast majority of problems that people have with their cars. These are jobs that don’t require a lot of mechanical skill, but could save you a fortune in the long run.

Also see