Mixing High Mileage Oil with Regular Oil: What You Need to Know

When it comes to taking care of your vehicle’s engine, choosing the right type of oil is essential.

Some vehicles, particularly those with higher mileage, benefit from the use of high mileage oil.

However, situations might arise where you need to mix high mileage oil with regular oil. In this article, we’ll explore whether it’s safe to mix these two types of oils and the factors you should consider.

Understanding High Mileage Oil

High mileage oil is specifically formulated for vehicles that have accumulated a significant number of miles on their odometers.

This type of oil contains additives designed to address common issues associated with older engines, such as oil leaks, reduced compression, and increased oil consumption.

The additives in high mileage oil help condition seals, reduce friction, and provide better protection for engines with wear and tear.

Can you Mix High Mileage Oil with Regular Oil

While it’s generally safe to mix high mileage oil with regular oil, there are a few factors to consider:

1. Compatibility

Most high mileage oils are compatible with conventional or synthetic oils. However, it’s recommended to stick with oils of the same viscosity grade and performance level to ensure optimal performance and protection for your engine.

2. Oil Change Intervals

If you’re adding high mileage oil to your regular oil, keep in mind that the performance benefits of the high mileage oil might not be fully realized until you’ve completed a full oil change cycle.

Mixing oils during a mid-cycle oil change might not yield significant benefits.

3. Benefits and Drawbacks

Mixing high mileage oil with regular oil can provide some benefits, such as enhanced engine protection for older vehicles.

However, the effectiveness of the high mileage additives might be diluted when mixed with regular oil. For maximum benefits, consider using high mileage oil exclusively during your next oil change.

Best Practices

If you decide to mix high mileage oil with regular oil, follow these best practices:

  • Check the Owner’s Manual: Consult your vehicle’s owner’s manual for recommendations regarding oil types and mixing.
  • Maintain Consistency: If you choose to mix oils, try to stick with the same brand and viscosity grade to ensure consistent performance.
  • Monitor Performance: Pay attention to changes in your vehicle’s performance, oil consumption, and leaks. If you notice improvements, consider switching to high mileage oil exclusively.


In most cases, mixing high mileage oil with regular oil is not harmful to your vehicle’s engine. However, to fully experience the benefits of high mileage oil, it’s recommended to use it exclusively during a complete oil change cycle.

If you have concerns or questions about using high mileage oil or mixing it with regular oil, consult your vehicle’s manufacturer or a professional mechanic for guidance. Proper maintenance and choosing the right oil for your vehicle’s needs will help ensure the longevity and performance of your engine.

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