Before we talk about which motor oil is best for your vehicle we need to talk about the types of motor oil available. Motor oil can be segmented into four basic varieties—synthetic oil, synthetic blends, high mileage oil and conventional oil.

Synthetic motor oil:

Synthetic motor oil is a laboratory synthesis of precisely controlled ingredients created by oil engineers, scientists and chemists. When combined with a high-performance additive package, this results in an oil with the highest levels of lubrication and engine protection, generally offering better protection at startup, better cleansing qualities, enhanced durability and better protection against heat buildup.

Synthetic blend motor oils:

Synthetic blend motor oils use a mixture of synthetic and conventional base oils for added resistance to oxidation (compared to conventional oil) and to provide excellent low-temperature properties and are recommended for cars, trucks, vans and SUVs that regularly carry heavy loads, tow trailers and/or operate frequently at high RPMs.

High-mileage motor oil:

High-mileage motor oils are specially blended for older vehicles, or vehicles with higher mileage. Typically, 75,000 miles (120,000 kilometers) is the figure used regarding high mileage oil. Some high mileage, high-performance cars, however, will be better served by continuing to use a synthetic motor oil. That said, a special high mileage motor oil blend, with its unique additives and viscosity, helps reduce oil burn-off, helps in sealing oil leaks and helps improve combustion chamber sealing to help restore engine compression. It all adds up to enhanced performance in older engines.

Conventional motor oil:

Conventional motor oil is what its name implies—it uses base oils enhanced in the blending process with chemical additives to help meet the manufacturer’s desired levels of heat tolerance, breakdown resistance and viscosity (viscosity simply being a technical term for the thickness and fluidity of the oil). Conventional motor oil can be had in a range of viscosity grades and quality levels, from adequate to an extensively designed, high-quality lubricant. Conventional motor oil is recommended for drivers with low-mileage, late-model cars whose driving habits can be described as routine—commuting, running errands, vacation driving at relaxed cruising speeds.

Today more and more engines require synthetic oil, so be sure to check your owner’s manual to make sure you don’t invite avoidable engine problems or void your warranty.

Oil Grade:

The next thing we need to talk about is Oil Grade. Oil grade is referred to by the numbers on the front of the oil container.

Motor oils use a rating system developed by SAE, which is the Society of Automotive Engineers, to classify oil by viscosity. We’re all used to seeing designations like SAE 5W-30 or SAE 10W-30. For multi-grade viscosity oils, the cold-temperature viscosity is labeled with a “W,” which stands for “winter.” Thus, in an SAE 10W-30 oil, the “10” is the cold-temperature viscosity rating, and the “30” is the high-temperature viscosity rating. This combination provides an oil that flows well at low temperatures, but still protects the engine at high temperatures. For comparison’s sake, SAE 5W-30 and SAE 0W-30 will flow better at even lower temperatures than 10W-30 while still providing protection at high temperatures. Just remember, the “W” stands for winter.

When it comes to these numbers follow your owner’s manual as to what is recommended. That’s really important. Using the wrong viscosity can end up in reduced lubrication and shorter engine life.

The API/ILSAC “Starburst”

You see this symbol on many quality oils. API is an acronym for the American Petroleum Institute. The institute’s Starburst stamp of approval—it reads “American Petroleum Institute Certified”—was created to help consumers identify engine oils that meet specific performance standards set by vehicle and engine manufacturers. The Starburst identifies engine oils recommended for a certain application, such as “For Gasoline Engines.” To carry this symbol on the container, the oil must meet the most current requirements of ILSAC, which is the International Lubricant Standardization and Approval Committee, a joint effort of U.S. and Japanese automobile manufacturers. The Starburst is typically found on the front label on SAE 0W-20, SAE 0W-30, SAE 5W-20, SAE 5W-30 and SAE 10W-30 motor oils.

Another identifier on motor oil containers is the API “donut” typically found on the back label. It’s divided into three parts. The top half of the circle (2) indicates the API service rating, also called the performance level. The center of the circle (3) denotes the SAE viscosity, which we just discussed. The lower half of the circle (4) indicates whether the oil has demonstrated certain resource conserving or energy-conserving properties. In the top part of the donut the words “API Service XXXXX” (5) indicate the type of engine and performance the oil provides. API Service SN the current rating means “S” for Service Station oil (for gasoline engines) and N the current level of service. Or it will say “API Service CJ-4.” API service CJ-4 means “C” for commercial engines (diesel engines) and J-4 where J is the current performance level and 4 indicates a 4-stroke diesel (a 2 will be used for 2-stroke diesel engines).

Synthetic Vs Conventional Motor Oil?

Which is better? So in general research has basically come to the consensus that on a short term performance level, conventional motor oils can and will work as well as synthetic as well as synthetic blends. If your car’s manual calls for synthetic, then use synthetic, especially if your car requires a viscosity that only comes in synthetic oils like oW-20. If your manual doesn’t demand synthetic, there are still times you will want to use it such as in turbo or supercharged engines, high performance engines, and engines that are doing a lot of towing or hauling.

The main differences that will encourage you to choose synthetic over conventional motor oil is that synthetic oils tend to have better high and low-end viscosity performance in extreme hot/cold weather. These oils are also more resistant to wear and breakdown by oxidation and are resistant to sludge formation, leaving you a cleaner, freer engine. In the long run this will improve your horsepower just a tad, and help to maintain your engine, while slightly boosting fuel economy as well. However, they can cost 2 to 3 times as much as regular oil. For high mileage cars that have engines working extremely hard, synthetics are definitely your best bet.

If you’re leasing a car, and planning on turning the car back in at the end of the lease, there’s no reason you can’t save money with traditional motor oil.  Don't tell them we said that.  

Brand Name Vs Generic?

While you are always safe with a name brand, as long as you look for the two seals of approval we spoke about earlier, the API approval seals, there is no reason why you can’t save money on an off-brand motor oil. There really isn’t much difference when you compare synthetic to synthetic and conventional to conventional. No difference the average consumer is going to see anyway. The secret behind the performance of any motor oil, synthetic or conventional, generic or name brand is how often you change your oil and the quality and upkeep of your oil filter. Keep these changed often and you will get the most out of any approved motor oil you choose, extending the performance and life of your engine.

Mobil 1 120764 Synthetic Motor Oil 5W-30 is the top selling motor oil on the market and also our personal favorite. The reviews on it are outstanding and we’ve never had any issues with a single engine on it. It’s a reasonable synthetic at about $22 for 5qt. You’ll also see top brands such as Valvoline, Castrol, Chevron, and Pennzoil.  All are fantastic choices, but don't be afraid to click any of the links or images below and browse for sales and rebates on Amazon because unless you've got a solid favorite, there isn't much difference between the brands as long as they are approved.  Your oil probably needs to be changed soon!