What are the disadvantages of excessive engine oil for the engine?

[Piper]

Excessive engine oil can cause the following issues for the engine: During operation, the crankshaft and connecting rod big end will experience intense agitation, increasing internal power loss. It also leads to more oil splashing onto the cylinder walls, resulting in oil burning and exhaust faults. Therefore, the engine oil level should be maintained between the upper and lower marks on the dipstick. It is not enough to just top up the oil without changing it. Regularly checking the oil is correct, and keeping spare oil in the trunk is quite normal. Over time, engine oil performance degrades due to contamination and oxidation, and some consumption occurs. Simply topping up without changing can only compensate for the lack of oil quantity but cannot make up for the loss in lubrication performance.

[DeJesse]

I've been driving for over a decade. A while ago, I changed the engine oil myself and accidentally poured in a bit too much without careful measurement. Just a few days after hitting the road, the engine noise became louder, fuel consumption skyrocketed, and I noticed a burnt smell with blue smoke coming from the tail. When I took it to the repair shop, the mechanic checked and said the excessive oil caused the crankshaft to churn the oil into bubbles and foam, drastically reducing lubrication effectiveness and accelerating part wear due to increased friction. Even worse, the high oil pressure damaged the oil seal, causing leaks that contaminated the engine bay. The repairs cost over 800 yuan and took two days. Since then, I've learned my lesson: always measure the oil level within the marked range before changing, start the engine for a minute then shut it off to measure again—no more carelessness. Too much oil is no trivial matter; it seriously affects driving safety.

[DelMiles]

As a car enthusiast, I've studied mechanical knowledge and understand that overfilling engine oil can cause significant damage to the engine. Excess oil gets whipped into foam by the high-speed rotation of the crankshaft. These air bubbles entering the oil passages lose their lubricating function, increasing friction between parts and accelerating wear. Under high pressure, sealing gaskets may rupture, causing oil leaks that corrode other components. Even worse, the foam entering the combustion chamber gets burned, producing blue smoke that pollutes the environment and clogs spark plugs. The proper checking method is to measure the dipstick between the minimum and maximum marks when the engine is cold. If overfilled, drain the excess immediately. During routine maintenance, don't take shortcuts by pouring in extra oil, as these small mistakes can accumulate into major problems.

[JaceLynn]

As a practical person, my primary concern with excessive engine oil is the waste of money. Increased fuel consumption means burning more gasoline unnecessarily; insufficient lubrication accelerates engine wear, with repairs like spark plug replacements starting at hundreds of dollars; oil leaks cause contamination, dirtying the undercarriage and requiring cleanup. In the long run, the cost of fuel-efficient and high-performance driving is far less than repairs. During maintenance, measure the oil level accurately—don't overfill. It's better to add less initially and top up later, saving money and ensuring peace of mind.

[GiaLynn]

Focus on safety and environmental protection. Excessive engine oil can lead to unstable engine pressure, potentially affecting brake response; oil entering the combustion chamber and burning produces blue smoke, posing significant health hazards due to air pollution; poor lubrication increases accident risks. Regular oil level checks to ensure normal values enhance driving safety and reduce emissions.

[AdrianMarie]

Driving experience tells me that excessive engine oil can shorten engine lifespan: oil churning into foam reduces lubrication and accelerates friction wear; high-pressure leaks corrode other components; oil burning clogs spark plugs and limits functionality. Daily checks with the dipstick should ensure levels are between the marks to prevent these hazards and avoid major overhauls.