Is it okay to fill the engine oil to the maximum level?
2 Answers
Filling to the maximum level is acceptable as long as it does not exceed it. More extended information is as follows: Overview: Traditional dipsticks have clear minimum and maximum marks, and as long as the detected oil level is between these marks, it is fine. Ideally, if the level can be in the middle, that would be best. Filling the oil to the maximum level is acceptable as long as it does not exceed it. Additional Information: However, more oil is not necessarily better. The higher the oil level, the greater the resistance the engine faces (since the crankshaft needs to continuously agitate the oil in the oil pan to achieve splash lubrication). Ideally, the oil level can be maintained at a lower-middle position, where the engine's resistance is minimized. At the same time, lubrication performance remains stable.
A while back, I also struggled with this when changing my own engine oil. Filling the oil to the maximum mark isn’t ideal—it’s like a full cup of water that spills with the slightest shake. The safest level is around three-quarters between the minimum and maximum marks when the engine is cold, leaving some room for thermal expansion. Once, my old Ford Focus had its oil filled to the max by an apprentice, and the engine sounded muffled like it had a cold, plus fuel consumption increased by half a liter. Later, a seasoned mechanic explained that excess oil gets whipped into foam by the crankshaft, actually harming lubrication. If you want to keep it simple, fill it to just 2-3 mm below the max. Nowadays, the small oil bottles sold at gas stations are exactly 0.9 liters, which puts the level just right after topping up.
