While it’s important to ensure your engine has enough oil, adding too much oil can also be troublesome. Excessive motor oil will not only affect your engineering mechanical properties, but may also cause some parts to be scrapped prematurely, leaving long-term hidden dangers. Below, we talk about the symptoms that may occur after adding too much oil, and how to deal with them if you find that you have added too much oil.
How to Check if Your Engine Has Too Much Oil?
Before solving the problem, make sure that the engine oil is indeed overcharged. Doubt is one thing, seeing the true level is another. So the most reliable way is to check it yourself.
Park the machine on completely flat ground. A lot of heavy equipment works on uneven surfaces like construction sites and farmland. The ground is uneven, the oil will tend to one side, so the engine oil dipstick reading is definitely inaccurate.
The engine had just stopped. It is better to turn it off and wait 15–20 minutes. This is enough time for the high-temperature oil to flow back into the oil pan. It can also cool the engine slightly to avoid burns, and can also get accurate readings.
Confirm the Fluid Level with the Dipstick
- Locate and pull out the dipstick, which usually has a brightly colored handle for easy identification.
- Wipe the entire end of the dipstick clean with a rag or paper towel.
- Fully re-insert the dipstick back into its tube, ensuring it seats completely.
- Pull it out again and observe the oil level.
The dipstick has marks. It is usually “MIN” and “MAX,” or “ADD” and “FULL.” If the oil level is way above the “MAX” or “FULL” line, the engine has too much oil.
Other Signs Show You’ve Added Excess Oil
- Blue or White Exhaust Smoke: If unusual smoke comes out of the exhaust pipe, like smoke with a blue tint, it means that the oil has entered the combustion chamber and is burning.
- Burning Oil Smell: Excessive oil leaks or splashes onto hot exhaust components can cause a noticeable, pungent burning oil odor.
- Oil Leaks: Oil droplets or stains appear under the machine. Too much oil is likely to seep through the gaskets and seals.
- Rough Engine Operation: Engine oil-contaminated components make the engine idle unevenly and run roughly.
- High Reading on the Oil Pressure Gauge: If your machine is equipped with an oil pressure gauge, you might see an abnormally high or erratic reading.
What Will Happen if Engine Oil Is Overfilled?
So you confirmed that you did add too much oil, so is that a big problem? It depends on how much more is added. A slight overdose is usually only a minor nuisance, but adding too much, such as an extra gallon on a large diesel engine, can cause serious damage in a short period of time. Here are the main issues that can arise.
Crankshaft Aeration and Oil Foaming
Crankshaft oil foaming is the most typical and dangerous problem after adding too much oil. When the crankshaft is working properly, it rotates at high speed above the oil surface and will not touch the oil at all. But once the oil is full and the oil level is raised, the counterweight of the crankshaft will start “spraying”, stirring the oil up to the point of bubbling, and the effect will be like running a high-speed blender. Blistered oil is full of air, and air can’t make the oil film the engine needs. No stable oil film means key parts like bearings, camshafts and pistons lose protection. Then metal rubs directly against metal. The result is rapid wear and temperature rise, and in severe cases, it may even directly wear out or freeze the engine. Simply put, once the oil is stirred into foam, the engine is essentially “dry grinding”, which is a very high risk.
Excessive Oil Pressure and Blown Seals
When the oil is filled too much, the crankcase is filled with space that should be left for air. As soon as the engine heats up, the oil and remaining air expand together, and the internal pressure will surge far beyond the normal range. These pressures require finding an outlet, and the easiest “unbearable” things to do in an engine are various seals and gaskets. The front and rear main oil seals, oil pan gaskets, and valve cover gaskets of the crankshaft will be continuously pushed. It may only be a slight oil seep at first, but if the pressure remains this high, the seal will eventually break. For example, if the rear main oil seal is damaged, it is a major project—usually the engine and transmission must be disassembled, which is costly to repair and can cause long downtime. Simply put, excessive oil pressure will not only cause oil leakage, but may also cause the seal to directly “squeeze out”.
The Catastrophic Risk of Diesel Engine Runaway
“out of control” is the most dangerous and destructive problem after too much oil, and it only happens on diesel engines. A diesel engine’s speed depends on how much oil is injected. But extra oil can get sucked into the combustion chamber. This might happen if crankcase pressure is too high, squeezing oil past the piston rings. Or it could be from a leaking turbine seal. Either way, the engine will burn that extra oil as fuel. Once it starts “eating the oil”, the engine speed will completely lose control, and it will spin faster and faster, far exceeding its safe limit. There’s no point in you turning off the key because it’s already relying on the oil to supply itself “fuel”.
Two results usually occur: automatic flameout after the oil is burned out, or serious damage due to overspeed before the oil is burned out, such as a broken connecting rod, a broken crankshaft, or even direct engine lock.
Some folks try blocking the intake air to shut the engine down, but this is super dangerous. It can easily cause splashing, bursting, or hurt people. Put simply, once a diesel engine gets out of control, it’s an emergency. The results could be really bad.
Performance Loss and Component Fouling
When you add too much oil, the crankshaft stirs this thick, sticky oil inside, which creates a lot of resistance. It takes more effort for the engine to turn itself, and horsepower and torque will decrease. The machine will become weak and slow to react, and fuel consumption will also increase.
To make matters more troublesome, excess oil is sucked into the combustion chamber and cannot be burned cleanly, leaving behind a large amount of carbon deposits. These carbon deposits can clog the injectors and cover the top of the pistons, making combustion worse, power drop further, and emissions worse. For modern equipment with reprocessing systems, the burned engine putty will quickly block the DPF, and you may end up having to do forced regeneration or even replace the entire DPF, which is not cheap.
What Causes Excess Oil in Your Engine?
Knowing the cause helps stop it from happening again. Mechanical issues can sometimes be the problem, but most overfilling cases are just simple human mistakes.
Simple Miscalculation During an Oil Change
The person doing the oil change might misread the owner’s manual for the engine’s oil capacity. This is easy on large machines that hold many gallons. Or they just get distracted and add too much oil.
Incomplete Draining
Old oil won’t fully drain if the machine isn’t level. Or if the drain isn’t left open long enough. Either way, adding new oil will almost guarantee an overfill.
Fuel Dilution
This is a more serious hidden issue. In diesel engines, a faulty or leaking fuel injector can drip raw diesel into the cylinder. The fuel seeps past the piston rings and mixes with the oil in the sump. Over time, this slowly increases the total oil volume. Check your dipstick—if the level has gone up and the oil smells strongly of diesel, you likely have fuel dilution. It needs immediate attention.
Coolant Contamination
A head gasket or engine oil cooler lets coolant get into the oil system. This also makes the dipstick level rise. Oil with coolant looks milky, like coffee. It’s a sign of a major internal engine problem.
How to Remove Excess Oil From Your Engine?
If you find that you have added too much oil, do not start the engine. Even just moving the machine could cause the problems ahead to happen directly. It is actually very simple to drain the excess oil. There are only two common ways to do it.
The Drain Plug (Recommended Method)
This is the safest, cleanest, and most controlled way to get rid of extra oil. You can control exactly how much you remove.
- Parking: Park the machine on solid, level ground and set the parking brake. If the engine’s hot, be super careful—oil can burn you badly. Wear gloves for sure.
- Find the Drain Plug: Slide under the engine. Locate the oil drain plug on the bottom of the oil pan.
- Prep for Draining: Put your large drain pan right under the plug.
- Loosen Carefully: Use a wrench to loosen the drain plug. Once it’s loose enough to turn by hand, press it slightly inward to stop oil from leaking. Unscrew it slowly until the last thread comes free.
- Drain a Little Bit: Don’t take the plug all the way out. Pull it just away from the hole to let a small stream of oil flow. Let 1-2 quarts drain, then quickly put the plug back and hand-tighten it.
- Check and Repeat: Wipe the dipstick clean, recheck the oil level and see how much it’s dropped. Keep draining small amounts and rechecking until the level is right at or just below the “FULL” mark.
- Tighten the Plug: Once the level’s correct, use the wrench to tighten the drain plug to the specified torque. Don’t over-tighten—you could strip the threads.
Siphoning
Use this method if the drain plug is hard to reach. Or if you prefer working from the top. It’s usually slower. And messier too.
- Stick the siphon tube down the dipstick tube. Stop when it hits the oil pan bottom.
- Put the other end of the hose into your waste oil container.
- Use the pump to make a vacuum. Start pulling the oil out.
- Siphon 1-2 quarts at a time. Pull out the tube now and then. Check the level with the dipstick.
- Keep doing this until the oil level is right.
No matter which way, make sure to get rid of the waste oil properly. Most recycling centers or auto parts stores take used engine oil.
Conclusion
Adding engine oil is a common maintenance task, but it must be added properly. Adding too much oil can also have serious consequences. So add slowly, don’t go past the “full” line on the dipstick. If the seal is leaking oil or other parts are damaged due to Gado, replace the faulty part as soon as possible. FridayParts has a lot of high-quality, reasonably priced engine parts. There are also all the suitable equipment brands, which can help you restore the machine to working condition as soon as possible.
