7 Reasons Your Oil Smells Like Gas & How to Prevent

Jerry Wilson
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Reasons Why Your Oil Smells Like Gas

We all know that petroleum derived lubricants are going to have a bit of a smell to them. It’s the price to pay for using synthetic lubricants over the old “everyone knows what they are” lubricants.

However, there are a couple of ways that you can keep the stink from getting so strong.

Protect Your Garage

Even if you don’t leave the garage door open all the time, chances are your garage doesn’t have the best ventilation.

When lubricants sit around for long periods of time, they can start to absorb moisture from the environment and break down. Moisture and petroleum are an absolutely toxic combination. So if you leave the garage door up, moisture will get in the warmer areas or in the winter when it’s cold.

If you live in a climate where it gets cold in the winter, especially in a northern state, you’ll want to invest in a dehumidifier or a ventilation system that will help lower the moisture levels in your garage. It’s a small investment in return for a much lower chance of smelly lubricants.

If you live in a warmer locale, a dehumidifier would be a great investment.

Symptoms of Oil and Gas Mixture

Both kerosene and gasoline have different odors, but you smell one that is very similar. The scent is a dead giveaway that gasoline and kerosene have been mixed in your machine. While this is a very dangerous condition, it can be remedied easily by changing the fuel type.

Adding gasoline to kerosene is an easy mistake to make. The same pump is used for both and they are right next to each other.

The first thing you want to do before using gasoline that has somehow been contaminated with kerosene is to check that your fuel line has no leaks. Many times, the problem lies within the fuel line itself, not within the tank itself. If the line is leaking, stop using the kerosene in that line and clean the area where the leak is occurring.

There are several causes of this mixture accidentally taking place.

The first is the less common driver error that results in the pump being used for gasoline instead of kerosene.

The second and more common cause is a dirty fuel tank. Kerosene and gasoline are both petroleum products and as such they can become very dirty over time. Dirt in the fuel tank can restrict the flow and keep the engine from burning the fuel the way it’s supposed to.

Consequences of Gas Getting Into Oil

If you use your gas-powered lawnmower or piece of power equipment while the gas tank is open, you run the risk of gasoline fumes getting in your engine oil. If this happens, you avoid the gas’s direct effects, like smog, byproducts, and other chemicals. However, if the gas gets into your engine through the oil, you risk harmful effects.

First, gas that has been in your oil for longer than a few minutes will get past the oil filter. Second, if your oil level is low, it’s easier for gasoline to get in you engine. Third, if you run your engine with gasoline in your oil, you can harm your engine and your fuel system, which is the complex mechanical component of your vehicle that enables the engine to run with combustible fuel that is stored inside the vehicle.

The parts of your vehicle’s fuel system are very sensitive and need to be kept in good working order. So, let’s look at why gasoline might leak into your oil and what you can do to prevent it before your engine is exposed to too much gas.

How to Prevent Gas Getting Into Oil

"Gasoline" and "oil" are two very different oils. Lighter fluid and other oil additives will ruin your oil by causing it to get dirty quickly, smell and lose its sealing qualities.

Be sure you have the right oil in your car, SUV, tractor or boat.

And never mix other oils and fluids with your automotive oil or your equipment oil.

On top of that, check under your hood for any leaks.

And never overfill the crankcase in your car or equipment.

A pressure drop will occur when you fill the crankcase beyond the capacity of the pump or injector.

This can cause the air in the system to bleed off through the breather tube on the engine head.

Constant bleed-off of air from the crankcase can lead to oil getting into your fuel system.

When the oil gets into the fuel, you may smell the odor, especially if its cold.

New vehicles may have an additive that helps stop or prevent air from coming into the crankcase through the breather.

If you spill oil on the driveway, wipe up right away with a paper towel.

If you spill oil in the crankcase of your car or other equipment, have it replaced right away.

If you spill oil on the battery, you will need to clean it up right away.

Use hot water and dish detergent to remove the oil.


When your oil smells like gasoline, you’d think you’d go crazy worrying whether it’s damaging your car’s engine. In reality, your oil smelling like gas probably isn’t major issue to worry about. Still, you can easily prevent it from happening too. That’s why we’ve dedicated this post to explain why it happens and what you can do about it.

Here’s the deal: when oil first comes out the ground, it’s black, which is caused by its chemical makeup. It’s typical for the chemistry of the oil to eventually change as it gets refined. Whether you know the history of how your engine was constructed, or when it was last repaired, that can all contribute to whether the gasoline smell is harmless or a sign that you may have a problem in your engine.

You should always get any oil that smells like a gas additive checked out by a professional, but many auto repair shops can normally tell you if it’s only a harmless side effect of engine repair from a few days or weeks ago.