Types of Engine Oil

All About Mixing Different Engine Oils In Your Car

Published by: Chevron Technology | 16-Jan-2025

Your vehicle’s engine is a complex piece of machinery that requires proper care and maintenance to ensure optimal performance and longevity. One crucial aspect of engine care is choosing the right engine oil for your car and sticking to a consistent maintenance schedule. However, there may be instances where you find yourself needing to top up your engine oil and wonder if it’s acceptable to mix different types of engine oils. Let’s explore the potential consequences of mixing engine oils and why it’s generally not recommended.

TYPES OF ENGINE OIL

There are different types of engine oil, each tailored to specific needs and conditions. Understanding the distinctions is crucial for optimal vehicle maintenance. Here are the primary types of engine oil:

MINERAL OIL

Characterised by high viscosity, mineral oil is more prone to deterioration when exposed to elevated temperatures. While effective in certain conditions, its limitations make it less suitable for high-temperature environments.

SEMI-SYNTHETIC OIL

With additional additives for enhanced performance, semi-synthetic oil strikes a balance between cost-effectiveness and improved heat resistance. This type of oil is also used for its versatility and ability to provide better protection in various driving conditions.

SYNTHETIC OIL

Often labelled as ‘fully synthetic,’ this oil type boasts superior properties, maintaining its effectiveness even in extreme temperatures. Known for a longer lifespan compared to other types, synthetic oil is a top choice for those seeking optimal engine protection and performance longevity.

WHAT HAPPENS IF YOU MIX TWO DIFFERENT ENGINE OILS?

Mixing engine oils generally won’t damage your engine, but closely matching viscosities is crucial. Here are key points to consider:

  • Viscosity Basics: The left-hand number (5W or 10W) plays a pivotal role in indicating viscosity. It dictates the thickness of the oil at different temperatures.
  • Cold Starts vs. High Temperatures: Thin oils with lower viscosity are preferred for facilitating cold starts, while thicker oils offer superior protection in higher temperatures. The ‘W’ in the oil grade stands for ‘winter,’ indicating the oil’s performance in colder temperatures.

Understanding viscosity is paramount to achieving a harmonious blend of engine oils and ensuring optimal engine performance.

MIXING DIFFERENT BRAND OILS

Mixing engine oils from different brands introduces potential risks. This risk arises from the diverse production methods and proprietary additives employed by manufacturers. Consider the following points when mixing different brands of engine oil:

  • Risk Factor: Mixing introduces the potential for oils with different physical properties, posing a risk to engine health.
  • API Certification: While some argue that mixing is acceptable if both oils are API-certified, caution is advised.
  • Preventive Measure: Undertaking an oil change promptly after mixing is recommended to prevent potential long-term damage and avoid the risks of delaying an engine oil change.

SPECIFIC CASE: 5W-30 AND 10W-30 OILS

The mixing of 5W-30 and 10W-30 oils is generally considered a safe practice due to their close viscosities. Consider the following:

  • Viscosity Variation: Before mixing 5W-30 and 10W-30 oils, consider the density difference.
  • Temperature Consideration: The left-hand number indicates viscosity at lower temperatures, with 5W-30 being thinner and more effective in colder weather.

CONSEQUENCES OF MIXING ENGINE OILS

Here are some consequences you might face after mixing engine oils:

VISCOSITY ISSUES

Mixing oils with different viscosities can result in inconsistent oil flow, potentially compromising engine lubrication and causing increased friction.

ADDITIVE COMPATIBILITY

Engine oils often contain additives that enhance their performance. Mixing oils from different brands or formulations may lead to incompatible additives, reducing the oil’s overall effectiveness.

CHEMICAL REACTIONS

Different engine oils may use different base oils and additives, and mixing them can trigger chemical reactions that may produce sludge or deposits, reducing engine efficiency.

REDUCED PERFORMANCE

Mixing oils can lead to reduced fuel efficiency, increased emissions, and a decline in overall engine performance.

WARRANTY VOIDANCE

Some vehicle manufacturers specify the type of oil that helps maintain warranty coverage. Mixing different oils may void your warranty, leaving you responsible for any repair costs.

To enhance fuel efficiency, always use the appropriate engine oil. Here are some indicators that you might be using the wrong engine oil for your car.

FAQs

IS IT BAD TO MIX 2 DIFFERENT ENGINE OILS?

In general, mixing two different engine oils won’t harm your car’s engine. However, it’s important to closely match the viscosity of both oils as viscosity determines how well the oil performs at different temperatures.

CAN YOU MIX 10W-40 OIL WITH 5W-30 OIL?

Yes, you can mix them, but the resulting viscosity will be in between the two. For example, adding a quart of 10W-40 to an engine with 5W-30 should be fine.

That’s all about mixing engine oils. However, it’s crucial to adhere to your vehicle manufacturer’s recommendations regarding engine oil type and viscosity. While topping up with a different oil in an emergency might not cause immediate catastrophic damage, it’s not a practice to adopt regularly. For optimal engine performance and longevity, it’s best to stick to a consistent oil type and brand, such as Caltex engine oil. Also, make sure you avoid misconceptions about engine oils in India and ensure optimal performance.

This Article is written by Chevron Technologies In collabaration with Industry Expert