What if I put 5W20 instead of 0W20?
If your vehicle’s manual calls for 0W-20, using 5W-20 is generally not ideal and can affect cold-start protection and warranty coverage. In many engines the performance at operating temperature is similar, but climate, maintenance requirements, and manufacturer approvals matter. Always check the owner’s manual or consult a mechanic before switching.
Understanding the difference between the grades
Here is a quick explanation of what those numbers mean and how they influence performance in cold and hot conditions.
What the numbers indicate
The first number (0W vs 5W) describes cold-start viscosity—the oil’s flow when the engine is very cold. The lower the number, the thinner the oil at cold temperatures, which helps start-up lubrication. The second number (both are 20) is the oil’s viscosity at the engine’s normal operating temperature (around 100°C). In practice, 0W-20 and 5W-20 behave similarly once the engine is running hot.
Why manufacturers choose one over the other
Engine designers select a grade based on tolerance, fuel economy targets, and climate. Some engines rely on the thinner cold-start oil of 0W-20 for quicker lubrication on cold starts, while others are designed to run well on 5W-20. This choice can affect warranty coverage if the oil used doesn’t meet the specified grade and approvals.
Here are the main differences to consider when deciding whether to use 5W-20 in place of 0W-20.
- Cold-start performance: 0W-20 pours more easily at very low temperatures, reducing startup wear in extreme cold.
- Operating-temperature viscosity: At 100°C, both grades are typically rated around 20 cSt, so protection during normal driving is similar.
- Warranty and approvals: Using a non-specified grade can affect warranty coverage if damage is linked to the oil choice; ensure any alternative meets OEM approvals.
- Fuel economy considerations: The difference in friction at startup can influence efficiency, but the effect is usually small.
- Climate suitability: 0W-20 is generally preferred in very cold climates; 5W-20 may be acceptable in milder climates if the manual allows it.
- Compatibility with your engine: Some engines have seals or tolerances that respond slightly differently to viscosity changes; rely on the manufacturer’s guidance.
In summary, the key takeaway is to follow the OEM specification. If the manual allows either grade, your climate and driving conditions can guide your choice.
What could go wrong if you use 5W-20 instead of 0W-20
If your engine clearly specifies 0W-20, substituting 5W-20 can lead to noticeable effects in certain conditions, though many drivers may not notice a dramatic difference every day.
- Slow or uneven lubrication during very cold starts, potentially increasing wear in the first moments after startup.
- Possible changes in oil pressure readings or behavior on startup in some vehicles.
- Potential warranty or service-interval considerations if the grade isn’t aligned with OEM specs.
- A minor, sometimes negligible, impact on fuel economy isn’t impossible, particularly in winter when cold-start friction is reduced by using thinner oil.
- Uncommon seal or gasket interactions, though most modern oils that meet the same spec won’t cause leaks.
Overall, the risk is usually modest in moderate climates, but it increases in very cold conditions or if the manufacturer explicitly requires 0W-20.
When is it acceptable to use 5W-20?
There are situations where 5W-20 may be permissible or even preferred, provided the owner’s manual or a dealer confirms it. If both grades are listed as acceptable, you can weigh climate, availability, and maintenance plans in your decision.
- Manufacturer-approved alternatives: Some engines explicitly allow either 0W-20 or 5W-20 or specify a viscosity range including both grades.
- Climate considerations: In temperate or warmer climates, the cold-start advantage of 0W-20 is less critical, making 5W-20 a reasonable option if approved.
- Short-term or temporary usage: If you’re mid-cycle and cannot access 0W-20, using 5W-20 is more acceptable if the manual allows it, with a plan to revert at the next oil change.
- Top-ups and availability: For topping up between changes, ensure the oil you add meets the required specs and approvals.
- Reversion plan: If you switch to 5W-20, plan to return to the recommended grade at the next full oil change.
Always verify with the manual and ensure the oil meets API/ILSAC specs and any OEM approvals before proceeding.
What to do if you’ve already poured 5W-20
If you accidentally used 5W-20 where 0W-20 is specified, don’t panic. Many engines will run fine, but you should take sensible steps to minimize risk and plan a return to the correct grade at the next service.
- Check the owner’s manual for explicit guidance on acceptable alternatives and any warranty caveats.
- Monitor for unusual engine sounds, rough idle, or oil-pressure warnings, especially after startup.
- Schedule an oil change as soon as practical using the correct grade, rather than letting the non-specified oil stay in the system longer than needed.
- Avoid mixing oils long-term; if you must top up and only have 5W-20, try to complete the change to the correct grade at the next opportunity.
- Keep documentation of the oil change and be prepared to discuss with a mechanic or dealer if you have warranty questions.
In most cases, returning to the specified grade at the next change is sufficient to restore optimal protection.
Practical tips for choosing the right oil
Make informed decisions by following these practical guidelines when selecting motor oil for your vehicle.
- Always follow the exact specification in your owner’s manual, including viscosity grade and any OEM approvals.
- Check the label for API/ILSAC certifications and any engine-specific approvals from the manufacturer.
- Consider climate and typical driving conditions—extremely cold climates favor 0W-20, while milder climates may tolerate 5W-20 if approved.
- Avoid mixing grades for extended periods; if you must top up, use the grade most closely aligned with the spec and plan a change to the exact grade soon.
- Keep a small stock of the approved oil for top-ups and emergency changes, including a receipt and service record for warranty purposes.
Following the manufacturer’s guidance is the best way to protect engine longevity, maintain fuel economy targets, and keep warranties intact.
Summary
Using 5W-20 instead of 0W-20 is not usually recommended if your vehicle specifies 0W-20, because it can affect cold-start lubrication, particularly in very cold climates, and may have warranty implications. When both grades are deemed acceptable by the manufacturer, the choice should be guided by climate, driving conditions, and availability. In all cases, revert to the exact grade specified at the next oil change and verify that the oil you use meets all required specifications and approvals. If in doubt, consult your vehicle’s dealer or a qualified mechanic.
