Your coolant plays a vital role in your car’s cooling system. As it cycles around the passages in the engine and through the radiator, it removes heat from the engine and prevents it from overheating. You should always keep a check on your coolant reservoir to make sure that the level of coolant stays up to the fill line. Coolant is usually green or orange, so what does it mean if you see brown spots in there? When oil mixes with your coolant, it causes these brown spots or turns it dark and milky. This is a serious situation, and you should get it addressed right away! Keep reading and we will explain what causes this as well as what it will take to get it fixed.

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Why Is There Oil In My Coolant?

Engine oil and coolant both flow through your engine as it runs, although they perform separate functions and should always be completely separated. The main function of your engine oil is lubrication while your coolant removes heat from the engine as it is cycled through the system by the water pump. There are seals and gaskets inside your engine that prevent these two fluids from mixing as they flow through their separate passageways. If you notice oil in your coolant, it means that the seal between the two systems has become broken and the liquids have been allowed to mix. This could be the result of a blown head gasket, cracked engine block, or several other things. It is imperative that you immediately correct the issue and get fresh coolant and oil in the engine to avoid further damage.


Common Causes Of Oil Mixing With Coolant

Maybe you have noticed those brown spots in your coolant or a frothy mixture on your dipstick. The dreaded mixing of oil and coolant has taken place in your car’s engine. So, what caused this to happen? There are a few things that could be the culprit, so we will discuss those here.


  • Blown Head Gasket

The head gasket seals the cylinder heads to your engine block. This allows compression to build inside the combustion chamber, and it also allows coolant to flow through the passageways in the engine without leaking. When the head gasket blows, this seal is lost and the coolant and oil can mix together. In addition to a mixing of fluids, a damaged head gasket will likely cause your car to overheat as well. If you notice a white smoke coming from your exhaust pipe, this might mean that there is coolant making its way into the combustion chamber. Have a professional mechanic check things out right away. While the cost of a head gasket repair is at least a few hundred dollars, your bill will go way up if you do more damage.


  • Cracked Engine Block

Automotive gaskets are not the only thing that keep the coolant, or antifreeze, from mixing with the oil. The engine block itself also keeps these two fluids separate. If a crack develops in the block, then you might find the coolant mixing with the oil. Some people see oil in the coolant and know it’s not the head gasket. In that case, a cracked engine block might be the problem. If you notice oil leaks or coolant leaks on the ground under your car, then you might have a cracked block. You should take your vehicle to a mechanic for an inspection right away.


  • Defective Oil Cooler

An oil cooler functions in much the same way as your radiator. Engine oil passes through the radiator-type device and removes heat from the oil. This assists the coolant system in keeping the engine cool while running. While many gasoline engines do not have oil coolers, they are quite common on turbocharged vehicles. If this cooler develops a leak, then you will probably notice oil showing up in your engine coolant.


  • Cracked Cylinder Head

Similar to a cracked block or bad head gasket, a cracked cylinder head lets coolant mix with oil. The passageways may no longer be completely sealed from each other, thus the oil gets in contact with the coolant as they are flowing. If you notice a buildup of oil or gunk on your cylinder heads, then there could be a crack there. You should have it inspected right away as frothy motor oil in your crankcase is not a good thing!


How Much Will It Cost To Fix?

The answer to this question depends on the root cause of the problem. If you simply need to flush the fluids and refill the system with new coolant and oil, then your bill should be only a few hundred dollars. However, if you have an oil leak from a bigger problem like a cracked block, then hold on to your wallet. This repair might cost you $4,000 or more to fix! You might be looking at the cost of a full engine rebuild. If the block is unrepairable, then you will need a new engine for your vehicle.

Most people do not have that much extra cash sitting around. Instead of dumping all that money into your old car, then you should simply sell your car for cash to Auto Wranglers. You can get paid cash for your car regardless of its condition – even if it has oil in the antifreeze! We pay cash for cars across the nation, and we will buy yours too!


The Bottom Line

You opened your radiator cap to check your coolant level and noticed brown spots of oil in there. So, what should you do now? There are several things that can cause your vehicle to be leaking oil into the coolant system. If your engine overheats as well, then the cause is likely more serious like a blown head gasket or cracked cylinder head. Go ahead and have your car inspected by a qualified mechanic right away to reduce your odds of further damage.

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Can you drive a car with oil in the coolant?

While you can technically drive a car with oil in the radiator fluid, you should only drive it far enough to get it to a safe place to park. If your coolant has oil in it, then your engine will probably run hotter than it should. In addition, you may have a more serious problem that could lead to complete engine failure if you continue to drive it. Park the car and have it fixed as soon as possible.

How do I get rid of oil in my coolant system?

First, you will need to fix the root cause of the problem. Once you have corrected the issue, then you can simply flush your coolant system to remove all the old contaminated fluid. Open the fill cap and refill it with fresh new fluid. Also, be sure to check your oil for signs of coolant. You might need to go ahead and perform an oil change as well to make sure there is no coolant in your oil pan.

How do you know if you have a blown head gasket?

There are several symptoms you can watch for that might point to a blown head gasket. Those include loss of compression, coolant leaks, white smoke from your exhaust, fouled spark plugs, engine misfiring, overheating, and a check engine light. If you notice any of these symptoms, then have your car checked out right away.

What is the best way to solve this problem?

If you are a fan of DIY projects, then you might decide to tackle this yourself. You will first need to diagnose the cause of the problem. You might need to replace your head gasket or even repair your cylinder heads or engine block. Once the repair is completed, then you can flush the old contaminated fluids from your engine and refill with new fluid. If you do not think you are up to the task, then take your car to a mechanic or simply sell it to Auto Wranglers.

Does oil in the coolant system cause the engine to overheat?

Yes, oil in the coolant can cause your car to overheat. Coolant is much better at heat transfer than oil, so when oil becomes mixed in, the coolant loses its ability to remove enough heat from the engine. When too little heat is removed, then the engine begins to overheat. While there are additives that can help coolant work ever better, the best thing to do in this case is flush the system and refill it with fresh coolant.

What is the consequence of oil in the coolant?

When you find coolant in oil or vice versa, it can have some major consequences on your vehicle. First, it can cause your engine to overheat. Next, it can cause important parts of your cooling system like the water pump to fail. A failed water pump and overheating engine can lead to major damage like a blown head gasket or cracked cylinder head. If you notice oil in the coolant, then you should have your car repaired right away.