The Best Oils For High-Mileage Engines: Keep Your Baby Running Smooth

Using a quality oil that'll help sustain an engine as it starts to be deemed high mileage is a good idea, too. Once an engine approaches 100,000 miles—or even as little as 75,000 miles—it's common for seals to wear out, tolerances to open up, oil flow to decrease a little, and so on. Especially if it hasn't had its oil changed religiously at every manufacturer's recommended interval—or sooner. High-mileage-specific is chock-full of unique formulas that help keep the engine's insides clean. They also re-condition seals, resist burn, and possess other quality-of-life boosting benefits.

We've assembled a handy and thorough guide of the best high-mileage engine oils on sale; utilize it for your next change.

While we wish we had the time and equipment necessary to long-term test every single one of these oils, unfortunately, we don't. This is just a buyer's guide, but look forward to comprehensive multi-product testing in the near future. Utilizing our familiarity and experience with the brands of these specific engine oils, we weighed out each one for its cost versus its detergent content, type, weight (also known as its viscosity) availability, and other meaningful metrics. All are quality oils, but some will play with your car's engine better than others, whereas some are more universal. For more on our methodology, check this out.

Castrol GTX full-synthetic is a household name in the high-mileage oil game for a reason. It's a trusted formula for optimum prevention and protection. Castrol proudly reports that it has 130 percent better sludge protection than industry standards, in fact, it'll do its best to clean up any sludge left in the system from previous oil changes. It also possesses six times more wear protection than industry standards, and its full-synthetic formula possesses better thermal stability over semi-synthetic blends and conventional options—this means it'll keep components well-lubricated in the face of high heat.

Valvoline's entry in the high-mileage oil game comes with many pluses. It features a lot of the same friction modifiers, wear reducers, seal conditioners, and sludge reducers as the other formulas in this buyer's guide. But at a bargain price, especially up against the full-synthetic options. Therein lies the rub: Modern naturally aspirated and turbocharged engines won't run as well on a synthetic blend. This is due to their tighter tolerances, advanced variable valve timing systems, and finely engineered turbo oil passages. But still, while it might not be the best choice for your eight-year-old BMW 330i, it might be a prime candidate for your early Aughts V8 GM truck.

Raise your hand if you've tasked yourself with maintaining an old turbocharged Porsche, Volkswagen, BMW, Mercedes-Benz, or Audi. All by yourself. C'mon, don't be shy; you should be awarded for your bravery. For older European cars that run better with semi-synthetic oil coursing through their veins, Germany company Ravenol offers a very high quality solution. It's specially formulated for older turbocharged engines. This includes diesels, and has a lot of conditioners that prevent sludge, cut down on consumption, and even condition seals. Hey, anything to help any-age German engine from leaking oil.

Mobil 1's entry in the ring is just as solid as any other full-synthetic. It features a laundry list of additives and detergents that protect against heat, lubricate effectively, and cut down on sludge. Though, it's a little odd to claim it's good for a 10,000-mile oil change interval: It might be a better idea to stick to your manufacturer's recommended 3,000-7,500 miles (check your owner's manual).

Royal Purple is renowned for its high-performance, motorsports-centric oil formulas, and utilizes its experience in such a field for engines that need a bit more care in their older age. The Texas-based brand says this oil not only increases (or restores) fuel economy but is an especially solid option for turbocharged and gasoline-direct injected engines. It also has excellent wear-prevention compounds, including zinc, and protects against all forms of corrosion.

Pennzoil's High Mileage conventional oil doesn't really have any knocks against it. It has pretty much all of the ingredients that high-mileage engines benefit from, and even comes in a good variety of weights that will fit most folks' needs. However, the main reason we included it is because it's a sturdy conventional option: While most engines run best on synthetic, many still like conventional, more, especially if they're a few decades old. If you're sporting an old truck, off-roader, muscle car, or even moody Land Rover from the '80s and early '90s, you might prefer conventional. So, why not treat it to a conventional one that comes with all the added benefits of sludge prevention, seal conditioning, and friction modifiers?

All of these oils are top-shelf, and some are a little more specific in their application than others. But for the top two most universal choices, you can't go wrong with Castrol GTX Full Synthetic Motor Oil or Valvoline High Mileage with MaxLife Technology Synthetic Blend Motor Oil.

Here's the rundown.

To quote a previous post on The Drive, the common way that engine oils are measured and marketed in our modern era is with a two-part label outlined by The Society of Automotive Engineers (SAE): The first number is its cold startup viscosity indicated by a W (think winter), followed by a number for its hot or operating temperature viscosity. Some examples of common oil weights are 5W-30, 10W-40, 0W-30, and so on. These are known as multigrade oils.

Lower cold-start viscosity numbers are ideal for climates that see cold winter temperatures, as it ensures the most flow when ambient temperatures are immensely lower than the engine's operating temperature. The second number is its viscosity at 100 degrees Celsius (212 degrees Fahrenheit). Thus, with a 0W-30 oil, it will act as a 30-grade oil at hot or normal operating temperatures.

You've got questions. The Drive has answers.