A car won’t work without the right kind of engine oil. And when it comes to car oils, it’s easy to think that 5W20 is pretty much the same as 5W30, except for a small number difference.
You might not realize all the important differences between the levels of thickness these oils have. The five denotes how well the oil will flow in cold temperatures.
While having the same characteristics, a question may arise in your mind: can you use 5W20 instead of 5W30? Let’s check out.
Topic Summary
Understanding Motor Oil Viscosity
Motor oils are rated by viscosity, the measure of how resistant they are to flow (for example, 5W20 or 5W30).
The W stands for winter (how the oil performs in cold temperatures), and the number before the W indicates the viscosity at low temperatures, with the number after the W indicating the viscosity at high temperatures.
- 5W20: This oil is thinner at operating temperatures.
- 5W30: This oil is slightly thicker at operating temperatures.
Differences Between 5W20 And 5W30
- Thickness: 5W20 is thinner than 5W30 at higher temperatures.
- Fuel Economy: Thinner oils, such as 5W20, can slightly improve fuel economy because they offer less wind resistance to moving parts in your engine.
- Protection: Thicker oils, like 5W30, provide better protection under most normal, high temperature, high stress conditions because they have a more consistent viscosity.
Can You Use 5W20 Instead of 5W30?
Not to overextend this analogy, but a car’s engine oil has a viscosity (thickness) rating. But, it’s how the oil behaves at operating temperatures, being thicker or thinner, that can affect your car’s fuel efficiency and engine capability.
So, it’s good to be aware of the distinctions to help ensure your car runs smoothly.
1. Manufacturer’s Recommendation
Your first stop should always be with your vehicle manufacturer’s recommendation. Your engine has a design viscosity intended for it. If your owner’s manual specifies 5W30, it is better to stay consistent with that. Switching your oil viscosity to 5W20, for example, might cause engine problems.
2. Viscosity Differences
The 5W20 oil you’re using doesn’t have the added protection provided by the thicker 5W30 after the oil heats up.
Perhaps this isn’t a big deal, but using 5W20 in an engine designed for 5W30 might result in less engine protection because, as it happens, the engineering judgement behind the 5W30 recommendation is that the extra thickness under high temperatures, especially under high loads, better protects the engine over its life than the thinner grade. This is especially true in hot weather operating conditions.
3. Fuel Efficiency
Among them is the fact that 5W20 is slightly thinner than 10W30 meaning that, in theory, using 5W20 could allow the engine to function using slightly less fuel per km.
However, the difference in fuel efficiency will be minor in practice. And even if the vehicle’s fuel efficiency will improve by several percent, the added risk of using thinner oil could result in much costlier problems.
4. Warranty Considerations
If you’re still under warranty, the wrong oil could invalidate it. Manufacturers wouldn’t be covering you for engine problems that the wrong oil use might cause.
5. Climate Factors
You will do better with 5W20 in a colder climate because it flows better at cooler temperatures. You will do better with 5W30 in warmer climates or in the summertime because of its higher viscosity.
What Happens If You Use 5W20 Instead of 5W30?
But using a 5W20 instead of 5W30 could cause problems, especially for the engine. Both oils are 5W in cold temperatures (the W stands for ‘winter’), but 5W20 is thinner than 5W30 at operating temperature, which can mean better fuel economy but also less protection, especially in hot conditions, and under high loads.
At higher operating temperatures, 5W30’s more robust viscosity does a better job of maintaining the oil’s protective film thickness.
Oil that’s too thin, like 5W20, might not provide adequate protection or film thickness for engine parts. Running an engine whose design specifications call for 5W30 might speed up engine wear, potentially shortening the engine’s service life.
If you pull out a 2017 Audi S4’s owner’s manual, you’ll find instructions on how to use ‘5W30 ACEA Engine Oil‘. Always turn to your car’s owner’s manual to make sure you’re using the correct thickness of oil to make sure your engine stays healthy.
FAQs On Can You Use 5W20 Instead of 5W30
What Happens If I Use 5W20 Instead of 5W30 in My Engine?
Driving around with 5W20 in an engine where 5W30 was recommended can compromise engine protection, especially during high temperatures or at higher loads. Beyond that, 5W20 is a thinner oil, and it may not provide the same level of lubrication or engine protection as a 5W30 motor oil. This can lead to engine wear or components over time.
Can Using 5W20 Oil Void My Vehicle’s Warranty?
Absolutely, if your car’s manufacturer specifies 5W30 oil, and you fill the engine with 5W20 instead, then that could put you outside of warranty. Your car manufacturer will specify a minimum viscosity that your oil must address and a minimum viscosity that your oil must be to be covered by your warranty.
Will Using 5W20 Instead of 5W30 Improve My Fuel Efficiency?
5W20 oil is a little thinner, and there will likely be a small gain in fuel efficiency. However, most engines are designed to use heavier oils, and a slightly thinner fluid cannot compensate for the loss of engine protection and longevity that will occur with even a minor amount of fouled oil.
Is It Safe To Use 5W20 Oil in a Hot Climate?
5W20 should definitely never be used if your car specifies 5W30, as the thinner 5W20 might be insufficient against engine wear at high temperatures.
Can I Switch Between 5W20 and 5W30?
What you want to do is simply stay at whatever oil weight your vehicle maker recommends for year-round use. Some manufacturers will change the recommended grade of oil at extreme temperatures but only switch to a different viscosity if your owner’s handbook specifically calls for it. Don’t just think that because it’s cold outside, you need to switch from a 5W30 to a 10W30 or 10W40.
Conclusion
Technically speaking, you can use a 5W20 instead of a 5W30, but it’s not recommended unless your vehicle calls for it and your vehicle manufacturer has approved it.
You want to stay within the oil viscosity they recommend. That will provide the best engine performance, protection, and longevity.
You may want to check your owner’s manual or speak to your mechanic about changing your oil type.