Top up or change?

Drivers often wonder: if oil consumption is fairly high, what should you do — just keep topping up the oil regularly without ever changing it, or still do both the top-ups and the scheduled change? The argument for skipping the change is that roughly the same volume of oil “passes through” the engine over the course of a service interval as would have been poured in at the change if there'd been no consumption at all.

In reality, the answer is obvious. Oil constantly washes the products of fuel combustion off the engine's internal parts. Some of them settle in the oil filter, some in the sump. But the key point is that none of it leaves the engine in any way — it doesn't burn off and it doesn't leak out through worn gaskets. So the concentration of everything that directly affects the engine oil's quality and characteristics can only keep rising. And by topping up with fresh oil, you're simply making up for the volume of clean oil that burned off in the cylinders.

So the volume of oil topped up over a service interval can't have any effect at all on how long that interval should be — the oil needs to be changed regardless, and on time!

Also worth reading:

• How often to change your oil - all about the service interval
• Additives in oil cause irreversible harm to the engine
• Do you need to flush the engine, and how do you do it correctly?

Everything about the causes of oil consumption</content>