Synthetic Blend vs. Full Synthetic Motor Oil

Reviewed by

Anthony Harlin, ASE Certified Master Automobile Technician

Technical Reviewer at CarParts.com

Written by CarParts.com Research Team - Updated on January 5th, 2024

Reading Time: 4 minutes
Summary
  • Full synthetic motor oil provides better lubrication than conventional mineral oil. It’s engineered in a lab and contains additives that allow it to resist degradation.
  • Synthetic blend motor oil is a mix of synthetic and conventional mineral oil. This motor oil offers some of the benefits of complete synthetic lubricants while being more affordable.
  • When choosing between synthetic blend and full synthetic motor oil, you should consider factors like your driving habits, vehicle engine requirements, climate, and budget.

When it comes to keeping your car’s engine running smoothly, you need to use the right oil for your engine. Your owner’s manual will indicate the right motor oil viscosity, but most owners will still need to choose between a synthetic blend and full synthetic motor oil for their vehicle. These two motor oil types have been becoming more popular in recent years because of their various benefits. In this article, we’ll help you understand their differences so that you can make an informed decision for your vehicle.

What Is Full Synthetic Motor Oil?

Full synthetic motor oil is engineered in a laboratory to provide better lubrication between moving parts than conventional mineral oil. Synthetic motor oil also has additives that make it better at resisting molecular degradation in high temperatures. Detergents are also present in full synthetic motor oil, which helps clean the engine from impurities. Is synthetic oil better? Absolutely. Overall, these benefits give full synthetic motor oil longer lifespans, which means vehicles will need fewer oil changes.

Advantages of Full Synthetic Motor Oil

  • Degrades Less: Full synthetic motor oil is more resistant to chemical breakdown or oxidation when exposed to the extreme temperature and pressure found inside the engine. Oil degradation can cause sludge buildup, varnish or deposits, corrosion, viscosity change, and decreased engine performance.
  • Enhanced Fuel Efficiency: Full synthetic oil’s lubrication properties can reduce friction losses in your engine, improve fuel efficiency, and reduce harmful emissions. This can lead to cost savings at the pump and a smaller environmental footprint.
  • Higher Viscosity Index: Full synthetic oil has a higher viscosity index, which means the oil’s viscosity changes less when temperatures fluctuate. Mineral oils are more likely to thicken at extremely low temperatures, preventing the oil from circulating effectively within the engine. A lack of oil circulation can deprive engine parts of oil and cause engine failure.
  • Excellent Cold-Weather Performance: Full synthetic oil doesn’t become too viscous in cold temperatures, ensuring a quick start even in frigid conditions. This is particularly beneficial in regions with harsh winters.
  • Longer Oil Change Intervals: Full synthetic oil typically lasts longer than synthetic blend or conventional oil, which means fewer oil changes and less maintenance over time.

What Is Synthetic Blend Motor Oil?

As the name implies, synthetic blend motor oil is a blend of synthetic and conventional mineral oil. This motor oil offers some of the benefits of complete synthetic lubricants while being more affordable.

Advantages of Synthetic Blend Motor Oil

  • Improved Performance: Synthetic blend oil has some of the benefits of full synthetic motor oil, including reduced degradation and low-temperature performance. However, it won’t perform as well as full synthetic motor oil.
  • Better Low-Temperature Performance: Compared to conventional motor oil, synthetic blend motor oil offers better cold-start protection. Synthetic motor oil doesn’t need to reach a certain temperature before it can effectively lubricate and protect your engine.
  • Cost-Effective: Synthetic blend motor oil is more affordable than full synthetic motor oil. It strikes a good balance between the enhanced performance of full synthetic oil and the lower cost of conventional oil, making it a suitable choice for budget-conscious consumers.

How To Choose the Right Oil for Your Vehicle

The choice between synthetic blend and full synthetic motor oil will depend on factors like your driving habits, vehicle engine requirements, climate, and budget. That said, if your vehicle manufacturer states that the engine needs full synthetic motor oil, then you should always follow it. 

Your owner’s manual will specify the oil viscosity and type suitable for your engine. If the manual specifically tells you to use full synthetic oil, then you should stick to it. Deviating from the manufacturer’s recommendations could lessen the engine’s performance and reliability. 

Full synthetic oil might offer the highest level of protection against wear, corrosion, and sludge buildup. These properties are the reason why some high-performance sports cars require full synthetic motor oil. However, using synthetic motor oil in some engines can be overkill because it might not offer much benefit compared to using synthetic blend oil. 

You also shouldn’t be too confident in its ability, as some manufacturers that require synthetic oil might state that your vehicle only needs an oil change every 12 thousand miles, which is two times longer than the normal interval. This might just be too large of an interval. If this is the case, it might be advisable to conduct oil changes sooner just to be on the safe side. The last thing you want is to develop engine sludge, which can cause a multitude of expensive issues. 

However, if the manufacturer doesn’t indicate any specific blend, then you’re free to choose. If you live in a cold climate, using full synthetic motor oil could be right for you because it offers better protection and lubrication when your engine is still cold. On the other hand, if you’re on a tight budget and don’t drive to extremely cold places, a synthetic blend might be a good compromise.

The main deciding factor in choosing the right oil is your engine’s requirements. If it requires full synthetic oil, then never use a synthetic blend. Another factor to consider is that the manufacturer may state that you can go 12k miles between oil changes, which is twice as much as a semi synthetic or a blend oil.

Anthony Harlin, ASE Certified Master Automobile Technician

Overall, the choice between synthetic blend and full synthetic motor oil depends on your manufacturer’s recommendations, as well as your individual needs and priorities. While full synthetic oil offers the highest level of protection and performance, synthetic blend oil provides a budget-friendly alternative with many of the same advantages.

About The Authors
Reviewed By Anthony Harlin, ASE Certified Master Automobile Technician

Technical Reviewer at CarParts.com

Tony Harlin is a Master Gas and Diesel Diagnostic Technician with over 18 years of experience. He works full-time at a large independent automotive shop as a driveability and repair technician working on all types of vehicles with a focus on diesels. ASE certifications include A1-A9, L1 and L2, as well as X1.

Written By CarParts.com Research Team

Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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CarParts.com Research Team and Anthony Harlin, ASE Certified Master Automobile Technician