Motor Oil, Oil Types, Conventional, Synthetic, Synthetic-BlendWith all the different motor oil types on the shelf, it can be a real challenge to figure out what they all are and which one is right for your vehicle. Should you use conventional, Synthetic , or a synthetic blend motor oil? Let’s explore the different oil types, examine the manufacturing process, and determine the correct type for your needs.

The Purpose Of Motor Oil

I’m sure you have heard motor oil referred to as the lifeblood of the internal combustion engine. The truth is that motor oil is a crucial component of the longevity and performance of your vehicle. Your vehicle’s engine builds up friction when the internal parts rub together, which in turn creates heat. Consequently, the purpose of motor oil is to lubricate the moving parts in the engine and absorb excess heat. With the addition of various additives, motor oil performs other vital tasks too. For example, motor oil also:

  • Cleans Existing Sludge
  • Inhibits Corrosion and Oxidation
  • Neutralizes Acids
  • Prevents Sludge Build-up

Motor Oil Types

In general, there are two components of motor oil: base oil and additives. They produce base oil from refined crude oil. Refining crude oil removes impurities like sulfur, solid particulates, and waxy substances. Different refining techniques can determine the base oil’s properties, characteristics, and behavior.

The amount of impurities left after refining, determines the oil grade and type. Those impurities also affect how the oil reacts to both low and high temperatures. Most motor oil formulations consist of 70-90% base oil (depending on the grade), with the remaining 10-30% made up of additives.


In the beginning, all motor oils used in combustion engines were conventional (aka mineral) oils. Conventional oils are often the most inexpensive option since they require a less rigorous refinement process. First, the refineries clean and distill the crude oil (without substantial molecular changes made to the hydrocarbons), resulting in a high-quality base oil. Then they combine the base oil with the appropriate additives.

Many domestic auto manufacturers recommend using conventional motor oil. Furthermore, if you own a vehicle manufactured before the year 2000, or your vehicle has a simple engine design, then you should stick with conventional oil. Expect to change your conventional oil every 3,000 to 5,000-miles.


Full synthetic oil requires more refining, which changes the molecular structure of the base oil. The molecules in full synthetic oil are more uniformly shaped, with fewer impurities, so it has better high & low-temperature performance. Many auto manufacturers now recommend using full synthetic oil in today’s vehicles.

Every oil change service must replace the old oil with the specific, full synthetic oil noted in your owner’s manual. You may void your manufacturer’s warranty if using a different type of oil. European auto manufacturers of high-performance vehicles have recommended using full synthetic motor oils for more than ten years.

Additionally, full synthetic oils offer benefits like extended oil change intervals and improved performance for high engine temperatures. Expect to change your full synthetic oil every 10,000 to 20,000-miles.


Synthetic-blend motor oil offers a balance between the economy of conventional oil and the superior performance of full synthetic oil. In addition, synthetic-blend motor oil combines synthetic and conventional base oils with specific chemical additives to enhance performance. On average, expect to change your synthetic-blend oil every 7,500-miles.

Chemical Additives

All motor oils contain necessary additives to help the base oil reduce friction, absorb heat, slow corrosion, and prevent sludge from forming. Refineries engineer and rigorously test motor oils to determine which additives work the best for each motor oil type and formulation.

Castrol Oil Change in Pomona, CA

Our Castrol Express Oil Change specializes in an under-20-minute oil change, featuring a digital 20-point inspection for your convenience. We happily top off your vehicle’s fluids, check your tire pressure, and notify you of your next recommended oil change service. Maintaining the recommended oil change schedule is the most important thing you can do for your vehicle. Unsure of the correct oil for your automobile? Try the Castrol Oil Finder!


Stop in our Castrol Express Oil Change located at 348 E. Foothill Blvd., in Pomona; any Tuesday through Saturday between 8 am and 6 pm. You can also call us at (909) 316-6161 or visit us online to make an appointment.

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