Oil is one of the most important fluids you can get in a car, up there with the importance of the fuel itself, and without it you could be looking at some very serious phone calls and trips to the garage to sort out. So what happens if your car has developed an oil leak? How did the leak start? How can you tell? What do you do?
How to tell if your car is leaking oil?
Thankfully an oil leak is quite easy to notice, even if you’re not particularly checking for leaks. A few of the warning signs to look out for are listed below.
- Dashboard warning light. An easy one to start with, your oil light on the dashboard will warn you if the oil levels or pressure dips lower than you’d want. While it’s not a guarantee that there’s a leak, it’s an important warning to get the car checked at least.
- Dark puddles under your car. If you pull off the driveway or out of the car park and notice a dark brown or yellow puddle under where the engine was sitting, then there’s a good chance your car was dropping some fluids. If where you were parked is a shared space, then placing a drip pan (or simply a piece of cardboard) will confirm whether it was your car or another.
- Smell of burning oil. If there is an oil leak then chances are it’s going to drop onto some of the hotter parts of the engine, and that gives off not only a pungent smell but also sizzles away like a frying pan on a weekend morning. If you hear what sounds like bacon and sausages but instead of a mouth-watering smell you’re subjected to a strong, bitter stench instead, it’s best to pull over as soon as you can do so safely. If you can’t see anything out of the ordinary, it’s still worth getting checked by a professional as a burning smell could lead to more problems down the road if not seen to.
- Smoky engine. Similar to the smell of burning oil, if the oil drips onto the exhaust manifold it’s going to cause a rather smokey situation. If left for too long this and the oil could begin to damage the oxygen sensors or even break down gaskets.
- Overheating engine. If there’s not enough oil in the engine, then the pistons aren’t going to have the lubrication required for smooth movements, meaning they will, instead, grind against other parts of the engine. As they grind against these other parts, excessive heat will be generated which can cause your engine to seize.
- Low oil levels. If you carry out regular checks on your oil levels and feel that the levels are dropping faster than you’d expect, then there’s a good chance there may be a leak somewhere within the system.
- Oil doesn’t look right. Another way you can see if there’s an issue while checking your oil is checking the consistency and the colour. Oil should be dark brown or black, vaguely translucent and, unsurprisingly, oily. However, if when you check it’s more opaque brown and the texture seems to be more foamy, frothy, or milky, then you could be looking at a blown head gasket. This means that the oil and coolant has leaked into each other and you’ll need to get this checked immediately. Blown head gaskets can destroy engines, so fixing it before any lasting damage occurs is a must.
Why is it a problem if your car leaks oil?
The most obvious issue if your car is leaking oil is that your engine won’t be correctly lubricated, and if there isn’t enough oil running around the engine you could be looking at catastrophic engine failure incredibly soon. Even if you think the leak is only small, it can quickly get much worse, and if this was to happen while you were driving it would be a very expensive breakdown.
Aside from the mechanical issues that can occur following an oil leak, there are also environmental and economical problems that come with leakages. Oil is a pollutant, and if any of your leaking oil runs into waterways it can be harmful to both plant and animal life. Not only that, but any oil on your driveway, parking space or garage can become incredibly slippery, which in itself is hazardous to you or anyone else. Leaks on the road can make the road surface treacherous to drive on and can cause accidents to vehicles behind you. Finally, engine oil isn’t cheap, and even if you’re only having to make small top ups it will soon add up and you’ll find yourself spending much more money in the long run than if you just get the main issue fixed.
Why is my car leaking oil?
Your car could be leaking for a number of reasons, more than we have time to list out for you here, but we have put together a list of some of the more common reasons you could see a pool of oil under your car.
- Oil drain plug. The most common reason your car is leaking oil is the drain plug. Located at the bottom of the sump and accessible from underneath the car, it is used for draining oil ahead of an oil change, and should really be changed after each oil change, however many skip this step and put the old plug back in which can cause the o-ring to leak. After an oil change make sure it is tightened up correctly, and if you can see oil leaking from the plug, it may be time to buy a new one.
- Oil filter. Rusty oil filters, or loose filters, can often cause oil leakages. Again you could find leaks coming from the o-ring sealing, but it is easier to replace the entire filter than just the sealing. The filter should be changed every oil change, and if you see any rust on the filter, it is time to change not only the filter, but carry out an oil change too.
- Oil pan. The oil pan sits at the bottom of the engine, and gets damaged over time as road debris hits the bottom of the pan. If your pan is made of aluminium, these can crack after heavy hits, causing leaks. If you have a steel oil pan, you could find it rusting over time, with even the smallest of rust holes enough to cause oil leaks. You may also see leaks coming from the oil pan gasket or sealant.
- Valve cover gasket. Located at the top of the cylinder head, valve covers are a seal created to prevent oil leakage. As a result of the constant heat they are put under, these can often wear out over time and require replacing. Spotting a leak from the valve cover is quite easy, but if the leak is coming from the rear of the engine, using a mirror can help you locate these.
- Crankshaft and camshaft seals. Seals around the crankshaft, and camshaft, hold oil inside the oil, and the constant movement of these two components can cause the seals to wear out overtime. The crankshaft will have sealings at the front of the engine and against the gearbox, whereas the camshaft will usually only have one at the front of the engine. If you see engine oil leaking from the gearbox housing, it’s more than likely coming from the crankshaft seal.
- Cylinder head gasket. If your head gasket is damaged it can cause oil to leak into the combustion chamber or even into the coolant system. Alternatively leaks from the oil pressure channels near the head gasket can cause external oil leaks onto the engine. These are uncommon, but it can happen, and if you can see oil coming from between the engine block and cylinder head, you should check the head gasket as soon as possible.
- Oil pressure sensor. Usually found in the cylinder head or at the engine block, the oil pressure sensor is often made from plastic and can crack and leak as time goes on. However, they are usually quite a quick, easy and cheap fix.
What to do it your car is leaking oil
If you can, try and find where the leak is coming from. You may find that it’s quite a simple fix and try to fix it yourself – if you do this just make sure afterwards that your oil is topped back up to the correct level so as to avoid any major engine damage.
If the leak is more significant, however, then you’ll want to take it to your garage as soon as possible and have it looked over by a professional. If you’re concerned that driving could cause more damage than harm, then arrange for it to be collected and taken along – the sooner it’s fixed, the sooner you can get back to worry-free motoring.
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