What are the disadvantages of excessive engine oil for the engine?
2 Answers
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.
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.
