Why Motor Oil Is One of the Most Important Things for Your Engine

Nov 19, 2023

The oil in your vehicle’s engine is pretty incredible. Its job is to protect every square inch inside your engine where there is metal-to-metal contact – your piston rings, cylinder walls, valves, lifters, crankshaft, rod bearings, etc. - and to do it all within an inhospitable, sweltering environment. Not only that, but your motor oil has to do its job even when the ambient temperature is frigid cold. On top of all that, engine oil helps pull heat away from hardworking components, it helps to seal the piston rings and numerous o-rings to mitigate compression loss and fluid seepage, and the latest advanced motor oils even have sophisticated detergents and corrosion inhibitors to keep the inside of your engine sparkling clean.

Of course, in order for your engine to be truly protected, it has to be supplied with the correct oil, and modern, high-tech engines in particular have much more precisely defined lubrication demands than older motors. Thankfully, if you’re ever unclear as to what sort of oil to use in your car, truck, or SUV, online oil guides like the one at Liqui-Moly.com provide the answer.

As a rule, modern engines are designed with much tighter tolerances and smaller oil passages than older ones. That’s been one of the auto industry’s responses to the call for lower tailpipe emissions: by designing for lighter, thinner oils, engines can minimize their efficiency losses from pumping and dispersing oil. That makes oil “weight,” a measure of its ability to flow at a standard temperature, arguably more critical than ever; the smaller oil passages and tighter gaps between metal-to-metal interfaces on the engines of today mean that higher-weight oils might not be able to infiltrate all the small spaces they need to, leaving your engine susceptible to serious damage.

Moreover, most major automakers these days each have their own strictly controlled motor oil specifications. Teams of engineers study their motors as they are run day-in and day-out, tearing them down and inspecting for signs of premature wear, scoring, particulates, and anything else that might be undesired, and concoct oil additive packages to target any specific problem areas and ensure the level of performance they’ve envisioned for the engine. Each OEM oil specification is unique, well-researched, and labored over, so that the only way you can be sure you’re getting optimal performance and affording your engine the level of wear protection it needs is by selecting an oil with the proper OEM specification.

Liqui Moly’s online Oil Guide takes OEM specs into account when recommending motor oils for your vehicle, looking at the make, model, and model year so that it can select oils that meet the automaker’s strict standards. All of this can help save you money in the long run, by lowering the risk of premature wear and catastrophic engine failure.

We’ve all been told that it’s important to change our motor oil according to a specified mileage interval, but why? What makes old oil less able to provide the level of protection and performance needed by our engines?

There are two main culprits behind oil’s loss in performance over time: contamination, and heat. Recommended oil-change intervals are really a best guess as to how frequently the average driver should change their oil to be safe, but in fact, different use cases may produce difference schedules for oil breakdown.

Contamination, which may include dilution of the oil with other fluids, can come about with regular use as metal parts inside the motor gradually wear and produce fine metal particles that get washed into your oil and sit in suspension. Much of this particulate gets taken out by your engine’s oil filter, but not all, and as the miles rack up, your oil filter becomes less able to do its job effectively. It can also come about as a result of tiny quantities of gasoline and exhaust gasses leaking past the rings and into the crankcase over time, introducing small amounts of fuel and soot into your oil, and from water vapor cooling and condensing inside your motor. This water is usually boiled off while you drive, but in colder climates or on short drives where your engine never quite reaches operating temperature, some of it can linger behind.

Heat, and specifically heat cycling – where your motor oil goes from cool to operating temperature and then cools back down again – can gradually take away from your motor oil’s performance, as well. In essence, over time, your oil gets slowly “cooked,” and both the additive packages and the oil itself begin to break down chemically. Its properties change, leaving it less able to flow and form the protective film your engine needs to mitigate long-term damage from wear.

That’s why we recommend changing your motor oil according to a strict interval that takes into account any extra risk factors like the frequency of short drives, cold ambient temperatures, and poor fuel quality, as well as only using oil that meets your OEM’s stringent specifications.

Liqui Moly’s online Oil Guide only recommends oils that meet or exceed the manufacturer specifications applicable to your vehicle, making it an excellent place to start. Check it out now.