Coolant Mixed With Oil In The Lubrication System – Cleaning Tips

Antifreeze In Oil - Can Be Catastrophic, If Not Dealt With Quickly
Antifreeze In Oil - Can Be Catastrophic, If Not Dealt With Quickly

Professional installers offer the following information on cleaning coolant mixed with oil in the lubrication system.

So, The following information applies only to certain situations. Consequently, It is not applicable for all engines that have coolant mixed with oil.

Above all, Cleaning coolant mixed with oil in the lubrication system will only work, if there is no engine damage.

Coolant In Oil
Coolant In Oil

So, Engine gaskets do a great job of keeping vital components separated.

But, As time goes by they do degrade and can sometimes fail.

The two most important things to keep separated are oil and antifreeze.

They do not mix and can cause extreme damage if they do.

Consequently, The most common causes for this to happen are:

So, The engine cannot run with coolant in the oil for an extended period of time. Because, It will not take long for the antifreeze to start eating away at the engine bearings. Do not run an engine once coolant is discovered in the engine oil.

Coolant Mixed With Oil In The Lubrication System
Coolant Mixed With Oil In The Lubrication System

Therefore, Depending upon the amount of coolant and the amount of time involved, serious engine damage may not result immediately. In only those cases, the following cleansing operation may prove beneficial.

Note: Todays engine oils already contain additives to clean your engine. But, All additive packages deplete with use. So, As the additives act to perform their function they will be consumed. Hence, The importance of oil changes.

How To Clean Coolant Mixed With Oil In The Lubrication System

First, Determine the source and cause of the oil contamination and repair it.

Next, You are going to do a complete oil and filter change.

Consequently, Oil is cheap, compared to the price of replacing your engine.


Park vehicle on level surface, engage parking brake and turn off engine. If necessary, raise front of vehicle by driving it onto a ramp or by jacking it up.


Open the hood. Remove the oil dipstick. Remove the oil filler cap. (helps the oil draining process)


Once the vehicle is safely and securely supported, put on safety glasses, crawl under the vehicle. Locate the oil drain plug, which is on the bottom of the oil pan.


Position a container, such as an approved oil catch pan, under the drain plug. Make sure the catch pan is large enough to hold the volume of oil expected to drain out. (There may be more depending on amount of coolant in oil.)


Loosen the drain plug using a box-end wrench or 6-pt. socket. Carefully remove the plug by hand, making sure the catch pan is underneath the plug hole. Oil will flow rapidly from the hole, but allow several minutes for all old oil to drain out.


Wipe the oil pan threads and oil drain plug with a rag. Visually inspect the condition of the oil pan and oil drain plug threads and gasket. Buy a replacement drain plug if you have any concerns about the condition of the plug. Replace the drain plug gasket if needed (some OEMs recommend this). Once the oil is finished draining, reinstall the oil drain plug. Tighten with the correct box-end wrench or 6-pt. socket to the manufacturer-specified torque. (See owner’s manual.)


Locate the oil filter. Position an oil catch pan under oil filter to catch any residual oil remaining inside filter. Loosen the oil filter, and allow the oil to drain from the oil filter. Remove the oil filter. Check to make sure the filter gasket has come off with the filter. If it’s still clinging to the engine mounting plate, remove it and any remaining residue.


Place a light coating of new oil on the gasket of the new oil filter so it will install smoothly. By hand, install the new oil filter onto the engine by turning in a clockwise direction. Once the oil filter gasket first contacts the mounting plate gasket surface, tighten the filter according to proper directions. Generally, this is three-quarters to one full turn after the filter gasket contacts the engine. (NOTE: Cartridge oil filter replacement procedures may differ. See owner’s or service manual for instructions.)


Pour in the correct amount of new engine oil. (See vehicle’s owner’s manual for recommended grade, specification and amount.) Replace the oil fill cap and dipstick.


Safely lower the vehicle to level ground. Start the engine and run at idle for minimum of 30 seconds. Carefully inspect under the vehicle for oil leaks (especially by oil drain plug and oil filter). If leaks are visible, shut off the engine immediately and have the leaks repaired.


Remove oil dipstick and check for proper oil level, adding more oil if necessary. (See the vehicle’s owner’s manual for oil capacity and recommended oil level on dipstick.)

If You Waited Too Long Or Damage Was Extreme, Engine Could Look Like This.

If You Waited Too Long Or Damage Was Extreme, Engine Could Look Like This.
If You Waited Too Long Or Damage Was Extreme, Engine Could Look Like This.

These instructions are intended as general guidelines. Please consult your owner’s or service manual for specific instructions on changing the oil and filter on your vehicle.

Don’t be scared to repeat this procedure if necessary, Oil is cheap compared to engine repairs.

If you want to do an engine flush it is up to you. But, Note: Todays oils already contain additives to clean your engine. Some people are scared of chemicals and do not want to flush the engine with them.  So, If you have any reservations about disturbing sludge or deposits that may be holding your engine together, skip it. It’s up to you.


So, It is recommended to perform the above mentioned procedures in a timely manner. And, After the above procedures have been carried out, check the engine oil pressure. Finally, The engine may be placed back in service if those pressures are within the engine manufacturer’s requirements.

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