Fuel Getting Into Engine Oil – Causing Premature Wear Of Engine Parts

Fuel Getting Into Engine Oil - Causing Premature Wear Of Engine Parts
Fuel Getting Into Engine Oil - Causing Premature Wear Of Engine Parts

Fuel getting into engine oil is bad, because it will dilute the oil causing engine damage.

Because, fuel getting into engine oil, causes the oil to lose viscosity, lowering engine lubrication.

Consequently, fuel getting into engine oil, will reduce oil viscosity; causing the oil to thin out to a dangerous level.

Also, this results in, additional friction between the metal surfaces; causing premature wear of engine parts. So, fuel getting into engine oil is a condition caused by excess; unburned fuel entering the crankcase. Consequently, fuel getting into engine oil happens to all engines; but usually not to the extent to cause engine damage.

Fuel Getting Into Engine Oil
Fuel Getting Into Engine Oil

The oil films formed, are weakened and less capable of withstanding, high engine loads.

So, Where Does The Damage Start

One of the early signs of this happening is a, lifter ticking noise, caused by lack of lubrication. After that, engine bearings will begin to fail, lowering oil pressure and eventually causing, engine knocking sounds.

Usually, the first to go are the rod bearings, as they are last ones to get oil.

Rod Bearing Damage
Rod Bearing Damage

Furthermore, as the lubricant is being used up and replaced by fuel, the concentration of additives decrease. So, fuel is also diluting the engine oil additives that you need like; rust inhibitors, detergents and dispersants. Detergents help remove sludge that can build up in the engine over a length of time. While, the dispersants will keep the dirt from coming together.

So, as you can see, anything that can contaminate your oil, can do engine damage. Most of these issues can happen with antifreeze as well. But, we will talk about that one later.

Worn Out Camshaft Housing
Worn Out Camshaft Housing

However, there actually are some ways to reduce this from happening, if you know the signs.

So, Knowing The Cause, Effect, And The Fix, May Be All You Need To Save Your Engine

Cause Effect The Fix
Continued operation with stops and start. The fuel doesn’t burn off completely. Reduce the mileage change interval, to the strictest change interval indicated by the manufacturer.
Starting in the cold. The fuel doesn’t burn off well, because the combustion temperature is low. Wait for the engine to increase in temperature, before accelerating.
Problems in the injection system. The droplets of fuel being injected into the chamber are big, which leads to poor combustion. The injectors need to be inspected.
Poor combustion. The fuel isn’t burning off completely. Check that the combustion chamber and the injection system are working properly.
Worn-out engine parts: valve guides, injectors and wear. Conditions change in the combustion chamber, meaning it is no longer optimized. The engine needs to be inspected.
Excessive acceleration. Excess inflow of fuel. Worn injectors.
Mixture of rich fuels. Excess fuel. Inspection of the, injection system.
Faulty injectors. Can produce excessive inflow of fuel or inadequate fuel injection. It does not burn fuel as well, resulting in deposits. Inspection of the injection system.

Piston With Fuel Wash Damage
Piston With Fuel Wash Damage

So, the problem of fuel passing through to the crankcase, seems to have reduced in recent years. As a result, this seems to indicate that, current fuel injection systems have improved.


Above all, proper maintenance, is the most important part of owning a car. Therefore, to keep it running smoothly, your car highly relies on oil, lube, and oil filters. Furthermore, oil helps in lubricating, cooling, and cleaning the internal engine components. Because, with time, engine oil, becomes contaminated.

Always, keep your eyes open for, early signs of engine problems:

Fuel Getting Into Engine Oil
Oil Level Too High
  • Check your oil level, it could be low or it could be too high. Consequently, some manufacturers have actually added a new notch; above the maximum mark as a warning sign.
  • When you remove your dipstick to check your oil, Smell it !  Does it smell like fuel. If so, have it checked and repaired, before any damage happens.

Finally, metal-on-metal contact, is the enemy of your engine and that’s why, clean oil is the cure.

Thank You !