How Often Should I Change Synthetic Oil and Filter in My 2018 Subaru?

When it comes to maintaining a vehicle, the choice of oil can significantly impact the longevity and performance of your engine. For owners of a 2018 Subaru who drive less than 6,000 miles per year, determining the optimal frequency for changing synthetic oil and filters can sometimes be a bit confusing. Let’s break down the essential details to help you make an informed decision.

Advantages of Synthetic Oil

Synthetic oil, as opposed to conventional mineral oil, provides several advantages, including:

Stays cleaner for longer periods Doesn't break down like conventional oil Offers superior lubrication through molecular bonding

Molecular bonding between the oil and metal molecules in the engine means that the oil is less likely to run off or cause an oil-starved engine. Synthetic oil typically lasts longer than mineral oil, and the specific recommended mileage can vary based on the brand.

Note: Always refer to the maintenance schedule provided with your vehicle. For many Toyota models, the recommended schedule is one year or 16,000 kilometers (km).

Maintenance Schedule and Mileage

Given the information provided, it's generally recommended to change synthetic oil and filters every 5,000 to 7,500 miles. However, this can vary depending on the specific type of synthetic oil used. Here are some additional considerations:

Synthetic Oil Classes

Not all synthetic oils are created equal. Lubricating oils come in five classes:

Class 1: Dino oil without additives Class 2: Dino oil with viscosity controlling additives and some others for other functions (most conventional oils are Class 2) Class 3: Chemically highly modified dino oil molecules Class 4: Polyalphaolefins synthesized from ethylene Class 5: An ester type (super expensive, mainly used for aircraft engines and heat pumps, refrigerators, and A/C pumps)

Classes 1, 2, and 3 are not considered true synthetic as they come from dinosaur petroleum oils. Classes 4 and 5 are considered true synthetic. In Europe, only Class 4 and 5 are allowed to be sold as "synthetic." In North America, Class 3 is also allowed to be called "synthetic."

North American synthetics that are Class 3 may carry a small notice on the label saying "not for sale outside North America." The so-called synthetics for automobiles can be pure Class 3 or mixes of Class 3 and Class 4 in a range of ratios. There are also blends of Class 2 and Class 3 called semi-synthetic or blended synthetic.

Tips for Longer Lasting Oil

To make synthetic oil last longer, consider the following tips:

Brand Recommendations: Choose a reputable brand such as Amsoil, which is known for Class 4 content. Other high-quality options include Mobil 1, provided that its content still leans heavily towards Class 4. Price Comparison: Compare the price of the synthetic oil to conventional oil. A general rule of thumb is that if the synthetic oil costs four times as much as conventional oil, it can last four times longer. Regular Changes: Regardless of the brand and class, it's generally recommended to change the oil and filter every year or every 7,500 miles, depending on your driving habits and the specific oil you are using.

Conclusion: While synthetic oil can last longer than conventional oil, the frequency of changes ultimately depends on the specific brand and class of oil. By following the manufacturer's recommendations and considering the above factors, you can ensure your 2018 Subaru continues to run smoothly for a long time.