Can I use 5W20 instead of 0W20 in hot weather?
In hot weather, you can usually use 5W-20 if your vehicle’s manufacturer approves it; otherwise stick with the recommended 0W-20. This article explains why the choice matters, how viscosity ratings work, and how to verify the correct oil for your engine.
Understanding viscosity ratings and the 0W-20 vs 5W-20 difference
Viscosity ratings combine a winter (W) grade and a hot-temperature grade. The first number (0 or 5) indicates cold-start performance, while the second number (20) indicates viscosity at operating temperature. Both 0W-20 and 5W-20 share the same hot-viscosity class, but 0W-20 flows more readily when the engine is cold. In hot weather, the difference is typically less consequential if the oil meets the engine’s required specification.
Because hot-weather performance is driven by the oil’s spec as much as its viscosity, the key factor is whether your car’s manufacturer allows substituting 0W-20 with 5W-20. When in doubt, consult the owner’s manual or a dealership.
Can I substitute 5W-20 for 0W-20 in hot weather?
Before substituting, confirm with the vehicle’s official guidance. If the manual or the manufacturer explicitly approves 5W-20 as an alternative to 0W-20, it is generally acceptable in hot conditions. If approval isn’t given, or if the engine requires a specific oil specification beyond the viscosity grade, use the recommended 0W-20 to preserve protection, fuel economy, and warranty coverage.
Be aware that some warranties or service agreements require adhering to the exact viscosity and specification. Using an oil not approved by the manufacturer can affect warranty eligibility and performance compliance.
With that caveat in mind, here are the practical considerations that typically guide the decision.
Key considerations when evaluating substitution
These points help you weigh whether switching to 5W-20 is appropriate for hot-weather driving.
- Engine design and manufacturer guidance: Some engines tolerate 5W-20 as an approved alternative to 0W-20; others require the exact specification.
- Climate and usage: Hot-weather operation emphasizes reliable high-temperature lubrication; cold-start performance is less critical in hot climates but still a factor when starting from cold.
- Warranty and service requirements: OEM or dealer warranties may mandate a specific viscosity or oil spec; deviations can impact coverage.
- Oil specification and additives: Even with the same viscosity, the base oil, additive package, and API/ILSAC/GF-6 or ACEA specs matter.
- Manufacturer-approved substitution process: If allowed, follow the exact oil spec (e.g., API SP with GF-6) rather than focusing solely on the 0W vs 5W rating.
In hot weather, the hot-temperature performance of 0W-20 and 5W-20 is typically similar when both meet the same specification, but you must adhere to the manufacturer’s guidance to ensure proper lubrication and warranty coverage.
How to verify OEM guidance and select the right oil
To confirm the correct oil, use this practical verification checklist.
- Consult the owner’s manual for the exact viscosity and any approved alternatives for your model and engine.
- Check the oil bottle label for the specification (for example, 0W-20 API SP GF-6 or 5W-20 API SN Plus GF-6) and ensure it matches the vehicle’s requirements.
- Review warranty and service documentation to confirm whether substitutions are allowed.
- Consider your climate and driving habits; if a substitution is allowed, 5W-20 generally performs well in hot weather.
- When in doubt, contact the manufacturer’s technical support or a licensed mechanic for a definitive recommendation.
Following official guidance ensures proper lubrication and helps protect warranty coverage in hot-weather conditions.
Practical guidance for hot climates
Beyond official guidance, these practical tips help maintain engine health in heat when choosing between 0W-20 and 5W-20.
- Stick with the recommended oil if you are unsure about substitutions; the right oil protects engines across a wide range of temperatures.
- Perform regular oil changes with the correct grade and fresh filters at manufacturer-recommended intervals.
- Monitor oil level and engine temperature, especially in extreme heat or heavy driving.
In hot climates, maintaining the specified oil standard, along with regular maintenance and cooling system care, is essential for long-term engine health; the oil grade is one part of a broader maintenance strategy.
Bottom line
Whether you can use 5W-20 instead of 0W-20 in hot weather depends on the vehicle manufacturer’s approval and the oil meeting the specified standard. If the manufacturer explicitly allows it and the oil matches the required specification (API/ILSAC/ACEA), it is generally acceptable. If not approved, or if the documentation requires only 0W-20, use the recommended oil to ensure protection, efficiency, and warranty compliance. Always defer to the owner’s manual and official guidance for the final ruling.
Summary
Choosing between 0W-20 and 5W-20 in hot weather centers on manufacturer guidance and official oil specifications. The hot-viscosity grade (the second number) is similar for both, so performance when hot is typically comparable if the oil meets the engine’s specification. Substituting without explicit approval can risk warranty coverage and engine protection. Verify with the manual, consult the dealer or manufacturer if needed, and follow the recommended oil for your vehicle to ensure reliability in hot climates.
