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Can I use 5W40 instead of 5W30?

Author

Emily Sparks

Published Jan 15, 2026

In practice, this means that each oil is just as viscous at lower temperatures and will remain viscous at -30°C, however 5w40 oil outperforms 5w30 oils at higher temperatures, being effective up to ambient temperatures of 50°C, as opposed to 30°C.

What will happens if I use 5w40 instead of 5w30?

The engine will not be improved by mixing different oils. When synthetic oil is mixed with regular engine oil, the additives may have little or no effect. If you mix 1 litre of 5W30 with 5W40, there will be no harm to the engine, as long as it is mixed with 5W40.

Is 5w40 the same as 5w30?

5w40 oil is not thicker has it has a higher viscosity. 5w30 has lower viscosity hence it is suitable to use in hot or lower temperatures. 5w40 has higher viscosity hence it is not suitable at all temperatures. 5w30 is a multi-graded oil which is suitable to use in lower temperature.

Can I use 5w40 instead of 5w30 for BMW?

Registered. The Castrol oil that BMW used to spec was midway between a 30 and 40 weight. Anything from 0W30 to 5W40 will be fine if it has the LL-98 or LL-01 rating. You don't even need that if you are running shorter change intervals.

Can I mix 5w40 and 5w30?

you can mix 5w30 with 5w40, you won't notice much of a difference in regular temperatures, but if you have a high-end, luxury car or performance car, it might be a good idea to use the only 5w40, even in emergencies, as it might cause inconsistencies especially under load which can lead to unwanted damage.

32 related questions found

Is 5w40 good for petrol engine?

5w40 is better for starting your engine at low temperatures as it flows more easily at these temperatures. When the engine is running and hot, 5w40 and 10w40 have high viscosities and are equally effective in protecting against engine wear.

Is 5w40 good for summer?

Can You Run 5w 40 In The Summer? The new 5W40 is great for summer, with its great cold start specs and great performance. The soot load and dilution of fuel will determine how long you can go without interruption.

What does 5w40 mean in engine oil?

5w40 motor oil has a winter viscosity grade of five, meaning it's less viscous at very low temperatures, compared to, say, 10w40. It has a hot viscosity grade of 40, which means it is just as viscous as 10w40 at high temperatures but less viscous than oils such as 15w50.

What temperature is 5w40 good for?

5w30 oil is designed to operate at temperatures as low as -25°C, but is also a great choice for warmer climates that reach up to 25°C.

What other oil can I use instead of 5w30?

Performance. Both 5w30 and 10w30 engine oils have a similar SAE rating, meaning that they will perform the same at high or operating temperatures. The digits 30 indicates the viscosity of the oils when in high temperatures.

Is 5w40 synthetic oil?

Full synthetic 5W-40 motor oil is formulated to flow like 5 Weight oil from a cold start in winter temperatures and like 40 Weight oil once the engine has reached its normal operating temperature.

What does 40 mean in 5w40?

The viscosity of 5w40 motor oil is five, which means it is less viscous at very low temperatures than 10w40. The viscosity of this oil is 40, which means it is just as viscous as 10w40 at high temperatures, but less viscous than 15w50 at low temperatures.

How long does 5w40 last?

How Long Does 5w 40 Oil Last? It seems like even a good dinosaur can travel 7500 miles without being severely duty-bound. The 5W-40 syn should get you 7500 miles. It is safe to extend drain intervals by using an oil analysis, and then 10-15K intervals can be reached within a few months.

Can you use 5w40 in a diesel?

Our answer: Yes, you can certainly use 5W-40 in winter (and summer) in your Duramax. While 15W-40 is suggested as the predominant viscosity for your engine, GM does recommend 5W-40 for temps below -18°C (0°F).

What oil is better for hot weather?

Generally, you'll get the best protection in the summer when you use a thicker grade of oil, such as a 10W30 instead of a 5W30. Summer heat and the effects of thinning the oil out of engines make them require thicker oils.

What is the best engine oil for hot weather?

The best motor oil for hot weather is Valvoline Advanced Full Synthetic 10W-30 Motor Oil. Diesel Motor Oil from Shell Rotella T5 Synthetic Blend 10W-30. This is a full synthetic 10W-40 motor oil from Castrol Edge. The Valvoline High Mileage Synthetic Blend 10W-40 Motor Oil is a high mileage oil.

What cars use 5w40?

The 5W-40 viscosity is a prevalent recommendation for performance engines in European vehicles with gas-powered engines, and in American diesel pickup trucks. We offer 5W-40 oils for gasoline- and diesel-powered engines. If you have a modern European vehicle, consider Mobil 1™ Formula M or Mobil Super™ Synthetic Euro.

When should I use 5W40?

5w40 is better for starting your engine at low temperatures as it flows more easily in this environment. When the engine is running and hot, the differences are negligible; 5w40 and 10w40 both have high viscosities and are equally effective in protecting against engine wear.

Which engine oil is best?

  • Mobil 1 Extended Performance : Best Advanced Synthetic Motor Oil.
  • AmazonBasics Full Synthetic High Mileage Motor Oil : Best Budget Synthetic Motor Oil.
  • Castrol GTX : Best Conventional Motor Oil.
  • Shell Rotella T6 Diesel Engine Oil : Best Diesel Motor Oil.
  • Quaker State Synthetic Blend : Best “Get-it-Home” Motor Oil.

Can I use 10w40 instead of 5w30?

Your vehicle does not use 5W-30 oil. The recommended oil viscosity for your vehicle, according to Kia documentation, is 10W-40. If you drive the vehicle in exceptionally cold weather, well below 32 degrees, you can use 5W-30 oil but even 10W-40 is still perfectly OK to use if outdoor temperatures are below freezing.

What happens if you put the wrong oil in your car?

Using the wrong fluid can cause poor lubrication, overheating, and possibly transmission failure. A mechanic might not be able to reverse the damage, even by flushing the transmission. Mistakenly adding motor oil or brake fluid can also destroy your transmission.

Why is 5w30 oil so popular?

Why is 5w30 oil so common? 5w30 oil is one of the most commonly used motor oils because it is suitable for a wide variety of vehicles and engine types. 5w30's viscosity range means it can lubricate, seal, and protect an engine's internal components in a range of climate conditions.

Is 5w30 OK for my car?

You should always use the oil recommended by your vehicle's manufacturer. However, 5w30 oil can function in temperatures as low as -30ºC and as high as 35ºC, making it an ideal choice if you drive your car in a place with relatively high seasonal temperature variations.

Will any 5w30 oil work in my car?

If your car takes 5w30 oil and you put 5w30 oil in it, it'll be fine.

Is 5w30 OK for diesel?

Generally speaking, 5W-30 oil is recommended for petrol and light-duty diesel use. However, 5W-30 can suffice heavy-duty use if utilized in the appropriate climate (colder temperatures). During winters, it can withstand any amount of cold temperature and moderate pressure due to its excellent viscosity.