Does Ambient Temperature Affect Oil Viscosity?

Your performance car is your pride and joy. In fact, you can’t imagine why anyone would park theirs for the winter. Sure, the road salt isn’t any good for it, but you’re willing to wash it every day of the week if it means more wheel time. You don’t want to hurt its heart, though, and you heard an old timer say something about running different oil in the winter rather than the summer because the temperature has a direct impact on your oil.

That got you thinking: Should you be changing oil with temperature fluctuations to get the best longevity and performance out of your engine?

The answer is no.

Quick Explainer

Ambient temperature has a direct impact on oil viscosity, which is why changing oil to match the seasons was a common practice years ago.

Viscosity refers to an oil’s resistance to flow, and is the most important property of the oil. The best way to understand viscosity is to think of how thick a liquid is. Water has a low viscosity and is thin in relation to a fluid such as syrup. The same idea can be applied to oils.

The viscosity of an oil is described to us as its weight. This is nothing new. We’ve all heard of 30-weight or 40-weight oil. The closer the weight’s value is to zero, the thinner it is. So, in this example, 30 weight is the thinner oil.

The detail left out so far is that the viscosity provided is representative of a measurement taken at a specified temperature. As temperatures change, oil viscosity will change with it. Oil becomes thicker at lower temperatures, and slows down.

If the ambient temperature drops low enough, oil flow in an engine suffers if the viscosity isn’t kept in check. Back in the old days, the way around this was to switch to a thinner oil for the winter.

Nowadays, we really don’t have to worry much about this issue thanks to the multi-viscosity oils we all use in our cars. Yeah, that’s why they call it 5w30 and not just 30-weight oil. That “w” in the rating doesn’t refer to weight, though. It means “winter,” and it tells us how the oil will behave when it’s cold. At low temperatures – namely during startup – that oil will behave the same as a thinner oil, meaning your engine won’t starve for oil and destroy itself.

What happens if oil viscosity changes?

The beauty of multi-viscosity oils is that you don’t have to change oil between seasons. Just run what the manufacturer suggests all year long, and you’ll be fine. If you run a different oil weight, you’ll run into a plethora of wear issues.

Manufacturers decide which oil viscosity to run by considering temperature alongside a few different aspects. For example, engine tolerances is a major determining factor, as is fuel type. Engineers take the collection of unique factors presented by a certain application and determine which oil weight is optimal for the engine.

The right oil is thick enough to provide a proper layer of protection to the moving parts, but thin enough to move at the right speed to protect everything it needs to. Changing the viscosity impacts the oil’s ability to perform as needed, compromising lubrication and damaging your engine.

To make a long story short, the experts that built your engine recommend a specific oil for a reason. Your best bet is to listen to it.

The same thing generally applies to a tracked vehicle as well. However, if you’ve made special modifications or are pushing the vehicle exceptionally hard, consulting with oil specialists to verify oil selection might not be a bad idea.

What can you do to keep oil viscosity in check?

Oil viscosity is crucial to engine life. However, it’s only one of many things you can keep in check – and it’s not something you should generally toy around with. That doesn’t mean you can’t do anything to improve your oiling system, though.

Moroso is one of the biggest and best names to call on if you’re looking to up your oiling system in almost any way.

Everyone knows about the brand’s trick valve covers to keep oil in, but that’s not all it has to offer. High-capacity oil pans to keep high-revving engines fed; windage trays to keep oil sling from slowing down the crank; oil pumps to improve efficiency; and even dry sump systems are all on the roster. The company even has oil separators to keep your engine breathing at its best.

If you don’t think these mods are worth making, you’re sadly mistaken.

A bigger cam and better heads increase airflow, allowing you to rev further and make more power. At some point, you’ll outrun your oil supply and suck the pan dry, which is why you need a bigger pan. Oil slinging around the pan keeps the crank from turning smoothly as it smashes into the counterweights, which absolutely thrashes horsepower, and you never know when someone is going to make fun of your stock valve covers.

The point is that while you don’t want to mess with viscosity, oiling system mods are worth it – and you want a name you can count on when you make them.

To learn more about Moroso’s quality performance products, visit: https://www.moroso.com/