What's actually in car oil additives?
We've all seen the claims from oil additive manufacturers – but how do they work?
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If you've ever walked into a car parts store you'll likely have seen products that you add to your engine oil to improve your engine's health and lifespan.
It's a pretty bold claim – after all, if a tin of goo could help your car's engine last longer, surely we'd all be using them already? It's a fair point – but if you're of the opinion that these additives are just snake oil, you might want to read on. Because apparently there's actual science behind them.
Science not snake oil
Liqui Moly's been at the forefront of this additive technology for decades, and they're one of the few brands to actually explain how the active ingredients in their products help keep your engine running – and they're the first to admit that no one product works for all cars.
The brand's Oil Additive doesn't have the most imaginative name, but it does what it says on the tin. You add it to your oil – and it contains a solid lubricant called Molybdenum Disulfide (MoS2). This is a bit like graphite – the fine grey stuff you find in pencils. It coats all the surfaces usually touched by oil in your engine, and reduces friction, which in turn improves efficiency and helps reduce wear and tear. It's perfectly suited for older engines – and it's been on sale for 60 years, so chances are it works. You can see roughly how it works below – the red bits signify the 'smoothing' of imperfections on your engine internals.
A solid lubricant such as Molybdenum Disulfide coats engine surfaces, reducing friction
A chemical approach
Next up is a more modern approach to oil additives – something Liqui Moly calls Motor Protect. This is designed to help modern down-sized engines last longer. We've all wondered how small turbocharged engines putting out more than 100hp per litre will cope over the decades, and Motor Protect uses a chemical substance to reduce wear and friction, and is is effective for at least 50,000km. It's designed to cope with the much higher core temperatures of a modern turbocharged engine, and provides a chemical finish to metal parts in the engine – again reducing friction. You can see in the diagram below that the additive provides a chemical finish rather than physically reducing friction.
So far we've had a product that contains solid lubricants, and one that contains a chemical substance for protection. You can, perhaps unsurprisingly, combine both the ideas and create a product that gives even more protection.
The best of both worlds
Liqui Moly's product is called Cera Tec. It uses tiny ceramic particles as its solid lubricant, and these have the benefit of not being affected by the high temperatures you get in modern engines, so they last longer. On top of this you get the same chemical protection as in the Motor Protect additive, so it's the product to pick if you want the best internal protection for your modern engine. The diagram below shows how it gives you the best of both worlds – friction reduction and a chemical finish on your internal surfaces.
So there you have it – a brief chemistry lesson to help explain the world of oil additives. Hopefully you'll know what you're looking at next time you're in the car parts store.