Know What You Want for a Smooth Oil Change

November 20th, 2020 by

A man is holding a jug of oil at the store.

Motor oil is one of the most essential components of any engine. Without it, resistance due to friction can cause the engine to seize. Even if the engine could run, wear due to moving parts rubbing on each other would destroy the engine in no time. As one of the most frequent maintenance activities on any car, the oil change is quite familiar to most drivers, whether they do it themselves or go to the closest shop on the “oil change near me” list. But if the menu of oil options looks like a foreign language, you’re probably wondering what’s the difference from one oil type to the next?

We’ll break things down so you can make a more informed decision, whether you’re in a service bay or grabbing a bottle from the auto store to change your own oil at home. Generally speaking, there are no “bad” choices, but depending on your needs – be they budgetary or performance – there’s always a “best” choice. Consider this your introduction to the deep and technical world of motor oil!

A Bit of Background

If you want to experience just how big of a difference oil makes, rub your hands together. Then head to the kitchen, put a bit of cooking oil in one palm, and rub your hands together again over the sink. Your hands are now going to slide more smoothly when rubbed together. But motor oil serves more functions than simple lubrication!

As it circulates through the engine, the liquid oil picks up bits of debris and removes them, keeping surfaces clean. Oils contain additives to prevent corrosion and varnish, further extending engine life and fuel efficiency. Finally, the moving liquid in contact with hot engine components collects some of that heat and moves it elsewhere, helping to maintain appropriate operating temperatures inside.

While there are many types of additives that one can find in different oil products, even many unique oils in a single packaged blend, the average driver won’t be too worried about them. We’ll talk a bit about how to distinguish one product from another, but first, we’ll linger on the obvious and most important question most of you will have: conventional or synthetic?

Oil Types

If your oil change technician asks you what type of oil you want and your first thought is either “olive” or “the slippery type,” you’re not alone. But what should your answer be? There are generally four basic options: Conventional, Full Synthetic, Synthetic Blend, and High Mileage. You probably won’t need to give your technician any more detail than that. So what does each of these mean, and when would you want to use each one?


Conventional oil is essentially created directly from crude oil. It’s still a complex blend of base oils that are considered “natural,” plus the usual additives. Relatively low processing goes into refining these oils, so they don’t cost much, but they also don’t last long, usually needing to be changed every few thousand miles.

New cars will usually come with conventional oil because it is cheap and the car manufacturer isn’t going to be putting miles onto the car. It’s quite suitable for moderate or light-duty driving and, as a budget-friendly option, is highly recommendable for many drivers. Ask for conventional oil if you:

  • Usually drive 300 miles a week or less
  • Have a car under 75,000 miles total
  • Experience moderate driving conditions (low towing/hauling demands, low-moderate acceleration)
  • Want the least-expensive oil option

An image is showing oil flowing between rods and pistons.

Full Synthetic

Man-made lubricants fall under the “full synthetic” category. Synthetic oils are tuned to perform better than conventional oils at low and high temperatures. By requiring fewer additives to achieve good viscosity results, synthetics degrade much more slowly than conventionals, allowing longer periods between oil changes. Especially in extreme conditions – frequent heavy towing or high-rev “sport” driving – full synthetic oil is unquestionably a better performer than conventional.

Of course, this all comes with a higher price tag. A survey by AAA showed that while a conventional oil change would cost about $38, a synthetic oil change averages $70, nearly twice as much. Even factoring in that synthetic oil usually has a much longer service interval – it can be 7,500 miles or more depending on the product – it’s probably not worth it for the average driver to go full synthetic. Ask for this oil type if you:

  • Frequently tow or haul heavy loads above 50% of your vehicle’s capacity
  • Drive aggressively with high acceleration
  • Have a performance-oriented vehicle

Synthetic Blend

A blend of synthetic and conventional oils is often the best choice for drivers who fall in between the previous two categories. In a synthetic blend product, the synthetic oil components contribute to improved protection and durability while the conventional components keep costs down. A synthetic blend may only cost a tiny bit more than its conventional counterpart – with a service interval that’s generally around 5,000 miles. This is an excellent choice if you:

  • Usually drive over 300 miles a week
  • Have a car under 75,000 miles total
  • Experience heavy-duty driving conditions on occasion

High Mileage

The term “high mileage” can be confusing – it’s referring to your car, not the oil. Vehicles over 75,000 miles have experienced wear and tear. Gaskets, seals, and bearings just don’t fit together as tightly as they used to. High mileage oils are specially formulated to maintain and even restore the performance of oil seals. They also have a higher viscosity than other oil types with the same rating, so they provide a more consistent film between moving parts and won’t leak as easily as other types. While drivers who continue to put their engines to work will probably be better off sticking with synthetic, almost all drivers should consider switching to high mileage when their vehicle gets there. If your vehicle is over 75,000 miles, we recommend that you ask for the high mileage option.

A mechanic is filling an engine with oil after an oil change near you.

The Details

Now, if you find yourself in an auto store aisle staring at dozens of different oil products, you’ll realize that there’s a lot more to oil than the four general categories discussed above. The most important detail, after the type of oil, is the viscosity rating. That’s the “5W-30” part, to use an example. The thing is, viscosity changes with temperature – think of how easily cooking oil runs around a pan once it’s been heated – and combustion engines experience a huge range of operating temperatures. Therefore the viscosity of motor oil under both hot and cold conditions is a critical performance indicator.

The first part of the viscosity rating is to do with cold temperature performance. Oil that gets very thick (high viscosity) when it’s cold makes it harder for an engine to start and operate efficiently during wintery conditions. All oils are rated based on viscosity at 0 degrees Fahrenheit. A 5W oil will be thinner at low temperatures than a 10W and is, therefore, a better choice for cold weather operation.

The second part of the rating addresses high-temperature performance. At any time of year, once the engine gets going, it’s hot in there, and the heated oil will flow much more easily. Thinner oil doesn’t maintain good surface coverage as well as a thick oil, so it’s important that the engine oil resists thinning. This resistance to thinning can also be thought of as a consistency rating – how similar the high-temperature viscosity is to low temperature viscosity. A higher rating is more consistent, so a 5W-30 oil is more consistent than a 5W-20 and therefore performs better at high temperatures.

Most conventional oils are 5W-20, 5W-30, or 10W-30. The average driver should be much more concerned about getting the oil changed regularly than about getting the right rating. If you’re standing in the aisle picking one out for yourself, let these tips guide your selection:

  • Choose a lower-W rating if you’re in a cold climate – 0W is better than 5W, is better than 10W
  • Choose the highest consistency rating you want to pay for – 40 is better than 30, is better than 20
  • Avoid 10W in cold climates

Conclusion – Oil Changes Made Easy

The world of motor oil is vast and complex – each oil product is a blend of several base oils and additives, each of which serves essential functions and has unique merits. The effects of the interaction of the components are more important than the individual parts themselves. Just remember our helpful tips when you pick out your oil.

Conventional oil is great for keeping service costs low on new, light-duty cars. Vehicles that experience intense driving conditions should get full synthetic, while moderate-duty drivers will be satisfied with a synthetic blend. Owners of vehicles with more than 75,000 miles will prefer the high mileage variety, which will keep things steady for many thousands of miles more. And really, that’s all you need to know to ask for the right stuff the next time you visit Romeoville Toyota in Romeoville, Il, or your local oil change technician for an oil change!

Posted in Oil Change Near Me