What is engine flushing

So, here's the blunt question: do you need to flush the engine or not? If you type this question into any search engine, you'll get roughly a third of the answers saying “yes, absolutely,” another third saying “no, never,” and the rest will be somewhere in between, along the lines of “you should, but…” or “you shouldn't, except in some cases…”. It starts to feel like this question, much like the choice of oil brand, is closer to a matter of faith.

But that's only true at first glance. In reality there are entirely objective factors that, once you understand them, let you confidently make the right call.

So, on to the main point. What's the commonly accepted meaning of the phrase “engine flushing”? Most drivers associate that phrase with some kind of chemical (something like a “five-minute engine flush”) added to the old oil before it's drained, after which you can pour in the new oil, or with a special flushing oil poured in between the “old” and the “new” oil.

Working from that understanding of the question, drivers often run themselves ragged searching for the most effective “five-minute” flush, or the best-quality flushing oil. Quite a few even use products like this at every single oil change…

But what actually happens?

In reality, engine flushing is a genuinely necessary and important process, only it needs to be carried out in a completely different way from what's described above.

Let's start by recalling what any engine oil is made of. Straight from the factory it contains a number of additives, and at least one of them is specifically responsible for continuously cleaning the engine's internal parts. So by pouring a good-quality oil into your engine, you're already doing enough to keep it clean.

If you regularly and reliably pour the same good-quality oil into your engine, no additional cleaning procedures are needed for your engine at all! It's a different matter if you've just bought the car and its service history is shrouded in a certain amount of uncertainty for you. Or, say, you've decided to switch the brand, type or manufacturer of oil. In these cases, and a few others, the engine does need flushing, but not with chemicals and not with some special flushing oil — unless, of course, you're driving a Lada whose condition you couldn't care less about, and unless your engine is dear to you, if only as a keepsake.