Can All the Engine Oil Be Drained During an Oil Change?
2 Answers
Not completely, as oil extraction relies on compressed air to remove the old oil, typically extracting about 80% of it. Here are some precautions to consider during an oil change: Oil Change Intervals: For new vehicles under normal driving conditions, if synthetic oil is used, the oil can generally be changed every 10,000 kilometers, and in some cases, it can even be extended to 20,000 kilometers. Avoid Overfilling: The oil level should be slightly below the mark on the dipstick, and avoid overfilling. Excessive oil increases the crankshaft's rotational resistance, reduces engine output power, and the surplus oil may enter the combustion chamber, leading to oil burning, blue smoke emissions, and increased fuel consumption.
I've been repairing cars for over a decade, let me talk about oil changes. Gravity draining definitely leaves residue – there's always old oil remaining in places like the oil filter housing and corners of the crankcase. Nowadays, more advanced repair shops use vacuum oil extractors that can suck the oil pan cleaner through the dipstick tube, but truthfully there's still oil clinging to the engine's oil passages. Typically about 300ml of old oil remains after gravity draining, roughly 5% of the total volume. But don't obsess over this amount – regular oil changes are what really matter, as the cleaning additives in fresh oil will dissolve residual contaminants. The crucial thing is always replacing the oil filter – that thing holds about half a cup of old oil. During maintenance, have the mechanic wait an extra ten minutes after removing the drain plug to let it flow out more completely for better safety.
