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Why You Should Avoid Driving Without Oil Cap and Other Things You Should Know About Engine Oil Caps

Why You Should Avoid Driving Without Oil Cap and Other Things You Should Know About Engine Oil Caps

It is common knowledge that regular maintenance and servicing prolong the life of your car. Some car parts need more attention to ensure safety like the engine. And then there are other parts that most people overlook despite its importance such as the case of an engine oil cap. There are people who end up driving without an oil cap on, compromising safety and may lead to expensive damages.

Auto Repairs Are EXPENSIVE

How long can you drive without an oil cap?

You can drive the car for some miles without an oil cap and without any problem. However, the damages it may cause later can be costly.

What happens if you lose your oil cap?

Some traditional cars can perfectly run without an oil cap on because of the way their engines are designed. But if you are driving a modern vehicle you should avoid driving without it. Automakers put the engine oil cap for a reason. The purpose of the oil inside the engine is to lubricate the parts and cools it down if the engine overheats. Some of the components like rings, pistons, valves and nozzles heat up when running for long. The oil regulates the temperature of the engine, keeping it normal.


Driving a car without oil cap on can cause serious issues such as not starting properly after a certain interval or in need of expensive servicing or cleaning. Also, the oil in the engine plays a significant role in making sure driving long trips are safe and smooth. When the engine oil keeps on spilling, driving becomes riskier and may cause damage on the engine. Here are more specific possible damages:

Dust and Debris May Get Into the Engine

Without the oil cap on, dust and debris can get into the engine. Dust that enters through the opening of the cap is where the issue begins. While there are oil filters that can keep the dust and debris from getting into the engine parts, the debris will eventually affect how the engine functions.

The oil is there to lubricate the engine and to keep its part running smoothly, and a little dust inside the parts can cause friction. This friction then leads to excessive heat which is definitely not good for the engine. 

Pro tip: Always make sure that the filler opening is closed with a tight cap. Debris that gets inside the engine can cause wear and tear on the engine parts. Make sure that you shut the cap after every oil change.

Oil Escaping Out 

The major concern when driving without an oil cap is having the oil spray out of the engine. You have a serious problem when a significant amount of oil escapes constantly as it will lose its lubricity causing serious problems. The engine parts will suffer from a lot of stress and the engine can get damaged after some miles. 

How to sufficiently cover or seal until you get a replacement 

In case you only have one car you can drive and do not have an oil cap yet, you have to cover the hole to keep debris out and avoid spillage the best way you can before driving to the auto parts shop. You will need some masking tape, scissors or a knife and a towel. Do the following steps:


  1. Tightly twist the towel into a tube shape that fits the exposed gap where the oil cap is supposed to be.
  2. Cut the excess towel. This is important to prevent fire from starting due to oil contaminating the towel under the hood.
  3. Use a masking tape to wrap the makeshift oil cap. This serves as a temporary filter to the air getting into the engine and at the same time block the oil from escaping and soaking the engine.


Now you are ready to drive your vehicle to the closest location that sells oil caps for your car. But remember to keep your rpm’s down and prevent yourself from having a lead foot till successful replacement of your car’s oil cap.


What to do if the oil caps fall in the engine bay and you cannot locate it

It doesn't matter where your oil cap lands, you should find a means to find and retrieve it. While losing an oil cap in the engine bay may not cause immediate issues or any trouble at all when it comes to engine performance, you will want to get it removed. If you are comfortable doing it, you can do it by yourself. If not, then have a professional remove it. 


The oil cap could be trapped somewhere in the engine bay and may cause it to rattle. It can be very irritating, or worse case scenario, it can result in an extremely strong odor because it is melting–an odor that you and your passengers will definitely smell. 


You will be in more trouble if the pieces of the cap fall into the engine itself. It could get into your oil until it found itself stuck between 2 pieces of metal rubbing together in the car engine resulting in a lot of issues if it is not detected and resolved in a timely manner. 


Needless to say, it does not matter if the entire oil cap or a part of it is lost within the engine bay or landed in the engine itself, you need to take it to your local auto shop for them to check it.


Where to Find a Replacement Cap

There are many places where you can find an oil filler cap, but the most reliable and convenient source in getting your oil cap is through an auto parts shop. But if you have the time and want to save on money, a good alternative would be through online via Amazon or eBay.

However, there may be instances where you find yourself far from home and with no auto parts nearby. If so, you could not do online shopping or get an oil cap through a local auto parts shop. What you can do is stop at the nearest gas station to get a new oil cap. Do not expect a typical gas station to have the specific oil cap you would need. If you rather be accurate and acquire the right part with complete peace of mind, you can always go to your car’s dealership.


Not all oil caps are the same or universal. But some caps may be interchanged with 2 different vehicles. For example, do not expect that you can use an oil cap off of a Mitsubishi Eclipse and place it on your Chevy Tahoe. But if you can get an oil cap from a Chevy Silverado 1500 for your GMC Sierra 1500, there is a bigger chance that it may work depending on the model year. 


If you obtain it online or walk into a local auto parts store, chances are you will see a “universal” oil cap. Still, you need to be sure that prior to purchasing the replacement cap, you need to read the provided description and make sure that your car is listed as a correct match for the oil cap. 


Signs of a Loose Oil Cap


Prevention is always better than cure. Like most car issues, a loose or bad oil cap, have many signs that will tell you of an impending issue. One of the most noticeable red flags is the loss of oil within your car. This is because the loose or bad oil cap is allowing the oil to escape and spritz onto the engine bay, lowering the oil pressure, but also results in a vacuum leak, causing a mess on everything it touches. There is also a probability of the oil getting onto the hot engine parts that can create smoke under the hood and surface in front of the windshield which compromises safety in driving. It is best to have your oil cap checked or replaced when you start noticing any of these signs.

How to avoid losing oil caps in the future

Always make sure that the oil cap is put back on tightly after taking it off. You should always double check if the oil cap is put back tightly and correctly even if it has been taken off at an establishment or at an auto service shop. One trick to confirm that the oil cap is never left off is by putting the oil cap on or close to the hood latch to where the hood can’t be closed without putting the oil cap back on. This way, you are sure that the oil cap doesn’t fall down into the car and get lost. 

Is it normal for smoke to come out of an oil cap?

Seeing engine fumes when opening the oil filler cap is not a good sign. Smoke from an oil cap means bad news to your vehicle and its engine. But what does it mean? It depends on how much smoke is being emitted. If there is only a small amount, you do not have to worry much as it is nothing serious. But large amounts of smoke can be alarming. 


It’s easy to find out if the smoke coming from your oil cap is something serious or not. All you have to do is:

  1. Start your engine and let your car idle for some time.
  2. Slowly loosen your oil cap and remove it completely. 


If there is only a small amount of smoke coming out of the motor, there is nothing to worry about. However, lots of smoke blowing out with pressure is a red flag. You should take your vehicle right away to a servicing shop if the smoke seems to be contaminated with fumes too.


Note: Do not open the oil cap when the engine is hot. Also, make sure to close the tank with the oil cap when you are done. If you find any oil residue, clean it up. 


Why Engine Emits Smoke from Oil Cap

Smoke coming out of the oil cap can mean two things. First, it may be caused by hot fuel bypassing worn valve stem seals and rings. The other reason is due to the fuel bypassing worn rings and valve stem seals. 


The engine parts running smoothly will depend on the specific amount of tolerance between them. It is necessary for oil to flow to all the components of the engine to keep them moving without friction. Proper oil flow prevents machinery from locking or seizing.


Through time, the engine parts will start showing signs of wear and the seals will become thinner. Consequently, some of the games between the components become too much wider for oil to get onto places it should not be like the combustion chamber. Fuel dripping through the valves and piston rings and going into the combustion chamber, will turn into smoke with each firing shot of air-fuel mix. 

How to Address the Issue of Smoke from Oil Cap

When this happens, you need to check if the stem valves and pistons are damaged or worn out. The best thing to do is to replace both parts because the older parts will not be able to keep up with the pressure produced by the newly changed part. It may be tempting to only change the worn part but this temporary fix will only cost you more money in the future. If your vehicle is emitting lots of smoke with contaminated fume from the oil gap, replace all the related parts. 


Whatever your oil cap problem may be, it may be a loose or bad oil cap, or a smoke coming from the oil cap, you should address it immediately. A simple and small part like an oil cap is very important in making sure your car is running safely and smoothly. Avoid driving without an oil cap as much as possible but if you are left with no choice remember to have it sealed sufficiently before getting a replacement.