The main difference between conventional, synthetic blend, and full synthetic motor oils is their composition and performance characteristics. Conventional oil is refined from crude petroleum, synthetic blend is a mix of conventional and synthetic oils, while full synthetic is entirely man-made with enhanced properties.
The importance of quality motor oil cannot be overstated. But choosing the right oil for your vehicle can be confusing with all the options on the market today. Should you opt for conventional, synthetic blend, or full synthetic?
Here we’ll break down the key differences between these three major oil types. You’ll learn about each of their characteristics, typical oil change intervals, average cost, and at what point it makes sense to switch to a different type of oil.
In this article we will examine the three different types of motor oils that you can select from for your vehicle’s first and subsequent oil changes. We will learn which of these types might be the best choice for your car and driving conditions.
In all cases, if your car’s manufacturer so states, use the oil brand, type and viscosity rating he recommend. In particular, if he provides a specific oil specification for your car, make every effort to use that type of oil. The type of oil used will not affect how long it takes to change it.
Look for the specification information on the label of the oil you purchase. The folks who built your car will know best how to prolong its life. Check out your owner’s manual for this information.
More about oil viscosity and the benefits of selecting what’s right for your vehicle can be found here.
Types of Motor Oil
Motor oil can be segmented into four basic varieties – synthetic oil, synthetic blend oils, high mileage oil and conventional motor oil.
While there are several factors in comparing synthetic vs conventional oil and synthetic blend vs full synthetic, there are unique characteristics and specifications to help you determine which oil is the best fit for your vehicle.
Synthetic Motor Oil
Synthetic motor oil has gone through a chemically engineered process. Synthetic oil molecules are more uniform in shape with fewer impurities and better properties than conventional oil molecules.
In most cases, synthetic oil has better extreme high temperature and low temperature performance. Synthetic oils are generally formulated with higher performing additives.
Synthetic Blend Motor Oil
The difference between synthetic oil and a synthetic blend is that a synthetic blend motor oil uses a mixture of synthetic and conventional base oils for added resistance to oxidation (compared to conventional oil) and provides excellent low-temperature properties.
High-Mileage Motor Oil
High-mileage motor oil is specially formulated for late model vehicles or newer vehicles with over 75,000 miles.
High mileage motor oil, with its unique additives and formulation, helps to reduce oil burn-off, and helps prevent oil leaks that may occur in older engines. Pennzoil sells many kinds of high-mileage motor oil.
Conventional Motor Oil
Conventional motor oils can be formulated in a range of viscosity grades and quality levels. Conventional motor oil is recommended for drivers with simple engine designs and regular (as opposed to severe) driving styles.
Motor Oil Grade Designations
Motor oils use a rating system developed by the Society of Automotive Engineers (SAE), to classify oil by viscosity. Viscosity is a fluid’s resistance to flow.
Fluids that are thin (like water) have a low viscosity, and fluids that are thick (like honey) have a high viscosity. Motor oil also changes in viscosity measurement as it is heated or cooled. SAE viscosity grades
Multi-grade viscosity motor oils are able to perform at a wide range of temperatures. For an oil with an SAE viscosity grade of 0W-20, the “0” is the cold-temperature viscosity rating (the “W” stands for “Winter”), and the “20” is the high temperature viscosity rating. Multigrade viscosity motor oil 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 colder temperatures than SAE 10W-30, while still providing protection at higher temperatures.
Always follow the vehicle owner’s manual to determine the correct motor oil specification, viscosity grade, and oil drain interval for your engine.
Conventional Motor Oil
Conventional motor oil is derived from crude oil and contains impurities. There are no additives added to the oil and it has irregularities at the molecular level.
Conventional oil will accomplish the basic task of lubricating your engine by coating the vital parts of your engine that run at high speeds and providing a barrier against engine wear.
Conventional motor oil will break down quicker than synthetic motor oil and require more frequent oil changes.
As conventional oil ages, it begins to leave carbon deposits in your engine forming “engine sludge” with continued use. This engine sludge can reduce the life of your engine.
In extremely hot or cold conditions, conventional motor oil can be susceptible to the elements. In high heat, conventional oil can start to boil off causing a loss of lubrication to engine parts running at high speeds.
In very cold conditions, conventional oil can become thick and less fluid, meaning it may not reach all of the vital engine parts quickly enough as the engine warms up, which can lead to damage.
Characteristics
Such lubricants are refined from crude petroleum stocks and then bolstered with a number of different additives. These additives help to keep internal engine parts clean, enhance lubricity, minimize the effects of moisture, keep contaminants in suspension and help the oil retain its viscosity over time.
Each of the major oil brands (e.g., Valvoline, Pennzoil, Castrol, Mobil, Shell, Amsoil, Redline, etc.) will have their own unique blend of additives. For this reason you may find a certain brand or brands that provide better fuel economy or quieter engine operation. Do not hesitate to take advantage of this knowledge.
Between oil changes, replenishing with the same brand installed at that last change is best. However, occasionally adding a quart of an alternate brand will not materially damage your engine.
Conventional oils do have some disadvantages compared to synthetic blends or full synthetic oils. The variable viscosity in a multi-viscosity oil like SAE 10W-30 or 10W-40 will gradually degrade. Over time this oil will perform more like an SAE 15 oil due to shearing of the oil molecules during engine operation.
Other disadvantages include: engine fuel economy may be poorer; buildup of carbon and sludge deposits may take place and during extremes of engine operation accelerated wear of dynamic components may occur. This especially applies if you live in an area with exceptionally high summer temperatures.
Average Cost
The primary benefit of conventional oil is that it is the lowest in cost of all the motor oils. Pricing can range from about $3.00 to $7.00 per quart. Prices may be slightly lower online or at discount department stores.
Typical Oil Change Interval
Because conventional oil viscosity degrades over time, the useful life of this lubricant is not particularly long. This behavior essentially limits oil change intervals to as little as 3,000 to 4,000 miles.
Synthetic Blend Motor Oil
Synthetic Blend oil is kind of like a hybrid of conventional oil and full synthetic oil. The two oils are basically mixed together so that you’ll have oil that is a little bit better than conventional oil.
Most blend oils will have a synthetic oil content varying from 10% to as much as 25%.
The idea behind the creation of such motor oils is all about offering some of the inherent benefits of synthetic oil, while still sticking to conventional motor oil as the prime component.
While these motor oils offer marginally better performance under extreme temperature conditions, compared to conventional oils, they do not provide the full import of the advantages that synthetic oils offer.
Characteristics
As with conventional oils, the blended (or semi-synthetic) lubricants include similar additives to improve oil performance. The somewhat disconcerting quality of this product is that the amount of synthetic added to the petroleum base will vary from brand to brand and may be as low as 30%.
No standards dictate the blending proportions for this product. And oil refiners closely guard their formulations. For this reason there is no concrete way to determine what you are getting for your money.
Some measure of the other synthetic benefits accrue to the blended oil. These include slightly better fuel economy; reduced risk of sludge and carbon buildup and improved high temperature performance.
Average Cost
Regarding cost, synthetic blend oils sit right in between the cheaper conventional oils and the full synthetic types. Expect to pay between $4.00 to $7.00 per quart for this type of lubricant.
Typical Oil Change Interval
With respect to oil change interval, plan to get no greater service life than you might with conventional oils. This is applicable because not knowing the blend ratio provides no guidance regarding the hope for an extended period between oil changes.
Is Synthetic Blend Oil Worth It?
Based on the nature of this product there is little to recommend its use vs. conventional motor oil.
Full Synthetic Motor Oil
Contains a mixture of additives that allow the oil to break down slower and provide greater lubrication for your engine. Synthetic oil offers better performance in extreme cold or extreme heat.
The synthetic oil flows and coats engine parts quicker in the cold of winter and break down slower in the extreme heat of the summer and continue to protect your engine from wear.
The benefits of synthetic also include extending the life of your engine. At the molecular level, synthetic oil is uniform. Due to a refining and purification process, it will keep your engine cleaner and last longer, resulting in a clean running engine for years to come.
Synthetic oil has also been shown to improve fuel economy and engine performance when compared to conventional oils.
Characteristics
Synthetic oil is manufactured in several different ways. Some synthetics use a petroleum base stock which is highly modified to enhance its qualities.
One manufacturer begins with natural gas as the base stock promising a more pure end product. Others begin with truly synthetic base stocks derived from several man-made chemical compounds.
As with the other oil types, additives enhance performance, but the synthetic qualities of this lubricant greatly benefit in four areas:
- First, these oils by nature are of lower viscosity than conventional oils. This reduces internal friction losses which enhances power and improves fuel economy.
- Second, this low viscosity characteristic is more effectively retained throughout the full temperature range of operation. Thus one blend, for example, an SAE 0W-40, can be used both summer and winter. Ease of starting in the cold, excellent cold engine lubrication and very effective lubrication at the highest of temperatures are all attained with full synthetic oil.
- Third, synthetics also are not prone to lose their variable viscosity qualities over time like conventional lubricants. They contribute to very low carbon and sludge buildup. Plus the lower viscosity greatly enhances the ability of synthetics to cool hot internal engine parts compared to conventional or even synthetic blend oils.
- Fourth, the long stable chain molecules of synthetic oils are able to sustain higher loads than conventional oils. This quality reduces internal wear adding life to any engine and may even help prevent LSPI.
The lower viscosity quality of the full synthetic oils and their enhanced slipperiness compared to conventional oils can introduce a minor problem in older engines. Thinner oil can pass through smaller spaces. Thus as a car ages, synthetic oil use can result in small oil leaks cropping up.
Some mechanics advocate switching to conventional oil if this occurs. From my perspective, occasionally wiping up a few very small puddles of oil in the garage is a small disadvantage vs. the enhanced engine life that accrues with these lubricants.
If your car’s engine is turbo-charged, synthetic oil is essential. The very high temperatures inside a turbocharger demand this oil type to avoid damage to the turbocharger’s extremely hot shaft and bearing(s).
Average Cost
The cost factor will have to be considered by some. Full synthetic engine oil prices can range from $8.00 to $12.00 per quart. Online procurement may be one of the best options to keep prices low, as is purchasing 1-gallon jugs at a time.
Typical Oil Change Interval
Due to this oil’s enhanced performance, oil change intervals can be extended. Some oil manufacturers indicate intervals of up to 15,000 miles between changes are possible.
I’d suggest caution in this regard. This distance may exceed the ability of an oil filter’s capacity for contaminants.
Comfortable intervals between changes could range from 6,000 to 7,500 miles if a high capacity oil filter is also installed with each change. And if your car came from the manufacturer with full synthetic oil in the crankcase, that auto builder’s recommended oil change interval should be followed.
Is Synthetic Oil Worth It?
Hands down synthetic motor oils are far better than conventional and blended types. In every respect, engine life and performance are enhanced.
The higher cost of these oils will be offset by longer engine life. This will be an excellent payback if you intend to own your car for many years.