Gray Oil In Engine: Causes And Solutions

Gray usually refers to metal particles in the oil. Your engine will face big trouble if you have enough Metal to discolor anything.

White/ gray colored oil is a sign of a coolant leak. Gray oil indicates that you may have a bad seal in your cooling system. Check to see if your coolant level has dropped recently.

If it’s gray and not milky looking, it’s only clutch plate garbage contaminating the oil. Graying is expected, depending on how long you have been on your engine. It needs to change the oil more frequently to protect your engine. Let’s learn the causes and solutions of gray oil in the machine.

Gray Oil In Engine

Common Causes Of Gray Oil In Engines:

The gray oil was usually the color of lead deposits from burning high-lead fuel of previous decades. Lead remains in the blowby, penetrates the oil, and is suspended by detergents in the oil formulation. However, it is doubtful that your oil is old, but the engine still contains lead.

Worn Aluminum Pressure Plate:

Due to the worn aluminum pressure plate in the clutch, your oil will be gray. Unfortunately, another source of gray is finely divided aluminum. This means something like an aluminum bearing has worn catastrophically.


Any water entering will be the culprit of gray oil in the engine. Some claim that a hot engine submerged in water can suck water into the crank through the vent hose. Water or coolant will also be responsible for the oil to foam. And it often leaves a gray sludge on your dipstick/oil cap.

Air cooling fins are shaped to dissipate enough heat in hot weather under power to keep it alive. So it gets much colder in the winter, making it harder for the water density to evaporate on short trips.

Coolant Leak:

When your coolant level is low, the clutch bottle is empty, and the oil is gray, you may have a coolant leak. Sometimes a low coolant can run hot, and overheating coolant can act on the crank. Use the steel clutch plates if your coolant level is good, but your oil is gray. You should change your oil after a few rides.


Condensation inside the engine is quite common during the winter months. It usually looks brown, although gray contains metallic particles. Condensation is also the culprit of gray oil in the engine.

Gray Oil On Dipstick

Is the oil gray on the dipstick? If the oil is gray, it’s not a gasket problem but a bearing problem. If it’s a metallic gray color, it usually means there are connecting camshafts or rod bearings that are destroying themselves.

In contrast, Metal, possibly steel, may be partly or entirely aluminum since it is lighter in color. It’s not a significant problem; stick a magnetic pickup tool in the oil if your dipstick tube allows it.

Moreover, it may be the cause of sludgy deposits. Check the oil regularly to see if the condition improves or worsens.

Grey oil In Lawn Mower

Do you want to know the causes of gray oil in lawnmowers? There are many causes of grey oil in engines. Coolant leak is the cause of gray oil in your lawn mower.

Check: Lawnmowers Oil Types

In an air-cooled engine, this can be from the wear of aluminum parts. An infrequent oil change can cause sludge to build up in the crankcase.

This could be from leaving it in the rain and snow. It’s because it allows water/condensation to enter into the crankcase. Additionally, if you use cheap oil, it also can cause grey oil in lawnmowers.

But the gray sounds like it’s running hot or has carb problems, such as gas cylinder washing and oil leaks. This also causes the culprit of gray oil in the engine Toyota.

Grey Oil After Engine Rebuild

Not gray looks like water; it should look like chocolate milk. It is not unusual to have some ultra-fine metals in the oil after rebuilding your engine. Likewise, it should no longer be present after the first oil change. After rebuilding your machine, if you see gray oil in the oil pan, it’s alright. But you have to be careful so that it doesn’t on the motor. After a 100-mile oil change, it shouldn’t go away because all the bearings are burnt out.

Some engine assembly lubricants cause “strange colored” oil after initial startup. Change the filter and oil if it shows up after your first start and test drive. Furthermore, you should check again after a few more miles.

How To Fix Gray Oil In Engine?

If your engine has gray metal particles, it will probably only be good once it shuts down completely. How to fix gray oil in your machine? Actually, it depends on whether it ended up in the oil or the cooling system.

You should do an oil analysis if it ends up in the cooling system. It’s because if it has contaminated the oil system, it usually severely damages the bottom-end bearings.

If oil analysis comes back clean, you can replace the gasket, material, or seal; it allows cross-contamination. Also, you put the engine back together, flush the cooling system, and get it running.

On the other hand, if it ends up in the oil system, that means you have a problem. Coolant, for some reason, usually has a severely detrimental effect on standard internal combustion engine bearing components.

That’s why you’ll likely need a complete rebuild after any significant amount of time has passed. It’s best to check the entire bottom, like the rod and main bearing. If something is damaged, it needs to be rebuilt.

Gray Oil in diesel engine

FAQ (Frequently Asked Questions):

Q. What color is bad engine oil?

Thick, dirty, dark brown, and sometimes black motor oil usually indicates that you have bad engine oil. The bad engine oils lead to a soot deposit.

Check: How Does Engine Oil Get Dirty?

The problem with soot is that sometimes it can accumulate into something large. Here the thick black texture can be more pronounced. Changing your oil is always good if you want to stay safe.

Q. Why gray oil in a diesel engine?

Like regular engines, the problem of gray oil in diesel engines is the same. If your diesel engine oil greys, it can cause water, condensation, coolant leak, and more. Nonetheless, you should find out the reason and immediately fix it.

Final Word:

In short, Gray oil in the engine usually means water that doesn’t show with an air-cooled engine. Your engine oil will be gray because of many reasons. Generally, if your engine collects condensation, you need to check your engine frequently.

The reason is that condensation can make your oil gray. On the other hand, above here, we have discussed the reason for the gray oil in the engine. At last, we hope you can get the proper solution to the gray oil problem. For further questions, please comment to us.


I am Engr. Z Eusuf Lubricant Specialist, Mechanical Engineer & has been working with engine lubricants for a long time and knows what makes them work best. I can help you find the right oil for your needs, and I have tips on how to keep your engine running at its best.