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Is High Mileage Oil Even a Real Thing? Everything You Need to Know For Your Next Oil Change


You'll feel a special kind of pride when your odometer crosses 100,000. With timely car repair, and if you keep up on your oil change schedule and other maintenance, you can make a car last what seems like forever. One man even has a Volvo at three million miles, still driving to this day. However, you need to know what matters and what doesn't. You'll hear a lot about high-mileage oils, half synthetics, full synthetics, etc, but do you know what it all means? When checking in for your next oil change, it will serve you well to know exactly what you're getting.

Synthetic Oil Versus Conventional Oil

You'll find untold numbers of debates and confusion about synthetic oil on nearly every car forum. And every time it's time for an oil change, this conversation comes up. There's good reason for that. The legal definition of "synthetic" is very loose. Many oil manufacturers would like the synthetic oil label only to be used with oils made without petroleum as a base oil. However, that's not the case. There are several groups of motor oil, and these determine whether they're considered synthetic or not.

Regardless, you're going to want to know what the difference is. Conventional oil is thick at low temperatures and thin at high temperatures. To fix this, oil companies use additives that will thin it out at low temperatures, and thicken it up at high temperatures. However, over time, these additives break down, and the oil goes back to the way it was.

Synthetic oil is different, however. Synthetic oils do not degrade the same way because they're designed at the chemical structure from the ground up. While a brand-new bottle of conventional 5w-30 will act like a brand-new bottle of 5w-30 synthetic, an old bottle of conventional won't. If you take your old synthetic oil after an oil change, however, it will be mostly the same as new synthetic of the same grade, perhaps a little thicker because it picks up contaminants. If you're willing to pay for the synthetic oil at your next oil change, it's better. You can put off your oil change longer, which will help balance out the extra cost of the synthetic.

High Mileage Oil Versus Regular Oils

If you look at most any high mileage vehicle, you'll see the majority of them have one thing in common: leaks. Because of this, the main thing high mileage oils do is carry conditioners. These conditioners react with "elastomers", a fancy word for rubber seals. Over time, the chemicals leach out of your engine's elastomers. The conditioners in high mileage oils act like a salve, healing your elastomers and helping them seal as well as they ever did.

Most high mileage oils have more than just the elastomer conditioners. They often have features like anti-wear additives, and dispersants and detergents to break up sludge and keep your engine clean. That is, if you get an oil change often enough.

So, When Should You Change to High Mileage Oils?

Companies like Valvoline suggest at 75,000 miles. However, if you pay attention, and you get an oil change regularly, you'll know best when you need it. If you're not seeing any leaks, and your engine runs smoothly, you probably don't need to make the change yet.

If you're looking for a reliable mechanic's shop to get your oil changed, West Coast Tire & Service is the shop you've been looking for. This multi-generational family business cares about you and your car. If you've got your own oil change story, share it on the West Coast Tire & Service Facebook page.