Can you mix high mileage and non high mileage oil? (2023)

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Is it okay to mix high mileage oil with regular oil?

High-mileage motor oil.

Mixing them will not improve the performance or efficiency of your engine in any way. Nor will mixing improve the oil performance, either. This is illustrated by these two equally important points: Adding synthetic oil to regular motor oil will not enhance the regular oil.

Does it hurt to mix high mileage oil with regular?

Yes. If it's something you do only occasionally, mixing shouldn't damage your engine. Let's say you want to top off your oil, just to keep you rolling until your next regularly scheduled maintenance check. Mixing is alright, if the oil you use is the weight (or viscosity) recommended in your owner's manual.

Is there a difference between regular and high mileage oil?

Regular oils will provide protection for your engine, but high mileage oils are specifically formulated with specific conditioners, seal compatible conditioners, antioxidants, detergents and additives to combat the issues that high-mileage vehicles often experience as they age.

Can you mix high mileage with full synthetic?

Myth: Full synthetic oil is not good for high mileage cars or older vehicles. The myth is rooted in the idea that synthetic oil is “slipperier”—lower in viscosity, or not as compatible with seals and will therefore leak or leak more in places conventional oil might not. Again, completely untrue.

What happens if you put high mileage oil in a low mileage car?

It can help reduce oil consumption, smoke, and emissions from older engines. High mileage oil also works to minimize leaks and oil seepage. While you could use high mileage oil in a younger car without harming it, the issues that high mileage oil addresses usually don't appear in vehicles with fewer than 75,000 miles.

Can high mileage oil damage a new engine?

Using a high-mileage oil in a new vehicle would be ill-advised, since no manufacturer recommends this type of oil for a new vehicle. Would it harm your engine? Most likely not, but it would be better to adhere to what is specified in the owner's manual, at least until the warranty has expired.

Does high mileage oil burn faster?

On older cars with 100,000 miles or more, increased oil consumption is to be expected. At the same time, many new cars require lighter weight oils — like 0W30 or 5W20 — instead of more traditional ones like 10W30. These finer oils smoothly seep by gaskets, rings, and seals, increasing oil consumption.

Can adding wrong oil damage engine?

Use only what the owner's manual specifies. Using the wrong oil can lead to reduced lubrication and shorter engine life. If the manual says to use synthetic oil, do so. Contrary to what some believe, adding synthetic oil to regular oil won't harm the engine, but there's also no benefit in doing so.

What happens if you mix 2 different engine oils?

Can oils of different grades be mixed? The good news is that mixing different types of oil it will not harm your engine in any way in the short run. Most synthetic and semi-synthetic engine oils are based on regular oil and are compatible.

How often should high mileage oil be changed?

You may be wondering “how often should I change my oil if my car has high mileage”? If you have a newer car with 150,000 or 200,000 miles you likely should also change your oil every 3,000 miles. If you burn more than 1 quart of oil or your oil is very dark before you get to 3,000 miles it's likely time to change it!

Does it hurt to mix full synthetic with synthetic blend?

Synthetic oil is entirely compatible with regular oil and synthetic blend oil.

Is it okay to switch from high mileage oil to synthetic?

You can switch from conventional motor oil to Mobil 1™ synthetic oil (and back again, if you want) without following any special procedures. There are two exceptions to this: a higher-mileage engine that has never used synthetic motor oil, or an engine that has used conventional motor oil and been poorly maintained.

What happens if you mix synthetic oil with full synthetic?

Mixing different types can destabilize your motor oil, reducing its efficiency and affecting your engine's performance. The smartest choice is to stick with the oil type and oil change intervals recommended by your car's manufacturer and visit your local car care experts for affordable services.

At what mileage should you start using high mileage oil?

There are two schools of thought about using high-mileage oils. The first is to switch when your vehicle reaches 75,000 miles. The second is to switch if your older vehicle is beginning to show signs of engine loosening. If you notice an oil drip, that's a sign you should start using high-mileage engine oil.

Is high mileage oil thicker?

High mileage oils contain viscosity modifiers that are durable and won't diminish over time. This causes the oil to stay thicker for longer periods of time, helping protect your engine parts.

How long can you go without an oil change high mileage?

Cars can generally go 5,000 to 7,500 miles before needing an oil change. Furthermore, if your vehicle uses synthetic oil, you can drive 10,000 or even 15,000 miles between oil changes. Continue reading to learn more about oil changes or skip to scheduling your oil change right here on our website.

Will high mileage oil cause leaks?

No, Ayesha, no oil will cause a leak, of any kind or type. High mileage oil simply contains detergents for your older engine. Nothing more. The cleaning detergents will not be the cause of a leak.

What is the advantage of high mileage oil?

Aside from preventing oil leaks, high mileage oils prevent viscosity break-down within these older engines. High mileage contains anti-oxidant additives which counteract any sludge that may be accumulating within the engine.

What happens if I put 5W 30 instead of 5W 20?

What happens if you use 5w 30 oil instead of 5w 20 oil? There may not arise sudden problems if your engine allows the use of different oils. If it doesn't, then the longevity of your engine is definitely at risk. Exposing your engine to somewhat thicker oil than it's used to leads to additional friction.

What happens if you put 10w40 instead of 5w30?

A common question is whether it's safe to use 10W-30 instead of 5W-30 oil, for example. While it's best to use what's recommended in your owner's manual, inadvertently using a viscosity one grade higher or lower than what's recommended generally poses no long-term harm.

What happens if you dont change your oil and just add more?

The wear down

The longer an oil change is put off, the engine in general will start to show problems. Most commonly, your engine will simply become too hot, which can cause it to run less efficiently. If the heat doesn't cause a gasket to blow, it will warp the parts of your engine.

Can you mix 2 different brands of full synthetic oil?


Even if two different brands of oil have the same viscosity, you still should not be mixing them together.

Can you mix 5w 20 and 5w30?

Yes, you can mix them. They will mix perfectly. In warm climates, they will act very similarly. Both are the same viscosity at operating temperatures.

Does engine oil expire?

Simply put, the shelf life of conventional motor or "lube" oil is up to five years. It's not something that goes bad in a couple of months. It's impossible to predict exactly how long motor oil shelf life is because petroleum stability (how well it resists change in its properties) is situation-dependent.

Do high mileage oils really work?

It's really a judgment call if you should pay more for high-performance oil when your vehicle has 100,000 miles on it but is using little or no motor oil. High-mileage motor oil doesn't hurt and it could prevent leaks from starting.

What are the disadvantages of synthetic oil?

A few disadvantages of synthetic oil to be aware of include: Probably the most glaring downside of synthetic oil is the cost. The price of synthetic oil is around two to four times the price of conventional oil. Synthetics may be more prone to additives precipitation during cold storage conditions.

Can you just add oil instead of changing?

Topping up your oil is typically not recommended unless the level is below the minimum mark. If you're running low on oil, however, topping off may help you get to your nearest Firestone Complete Auto Care for an oil change service.

How do I know if I need synthetic blend or full synthetic?

If you are on a budget then synthetic blend would be best for you. While full synthetic is more expensive. Full synthetic oils do not degrade as fast as synthetic blends. Full synthetic will need to be changed every 10,000 to 15,000 miles depending on your vehicle.

How long can you go on synthetic blend?

Synthetic blends and fully synthetic varieties can last 5,000 miles and up to 10,000 miles between oil changes. High-compression engines, auto start and stop technology, turbocharging, and more have put increasing demands on oil and lubricant technology.

Do I need full synthetic or synthetic blend?

Full synthetic oil offers longer oil change intervals and prevents sludge formation in your engine. However, synthetic blend oil is more affordable, can withstand extreme temperatures, and works well for heavy-duty use.

Is it OK to put synthetic oil in an old car?

Modern synthetic oil is safe to use in all types of vehicles, ranging from new purchases to classics to aging not-so-classics. The idea that synthetic oil could harm old engines probably comes from a time before synthetic oils had been extensively tested.

Is high mileage oil always synthetic?

High mileage oils are usually synthetic oils. They are typically based on either full-synthetic oil or a blend of synthetic and conventional oil.

When should you not use synthetic oil?

This being said, however, it is still not recommended to use synthetic oil in engines that have experienced significant actions – specifically, those that have reached around 75,000 miles on the odometer.

Why you shouldn't use full synthetic oil?

Risks of Using Synthetic Oil in Older Cars

This is because many synthetic oils contain esters, which are organic compounds mixed with alcohol. This particular combination can be extremely rough on seals within the engine, which can cause the seals to wear down and begin to leak or burn oil.

Is synthetic oil overkill?

Here's the thing: for most cars and their usage, synthetic oil is overkill. When it's serviced regularly, conventional oil does a good job protecting your engine. Some cars, however, require synthetic engine oil, no questions asked.

Is it worth it to use full synthetic oil?

Yes, synthetic oil is better for your engine than conventional oil. Although conventional oil (i.e., mineral oil) can provide adequate lubrication performance, it can't compete with the overall engine performance and protection provided by synthetics.

Is it OK to use thicker oil in high mileage engine?

A: Yes. This is a practical method to improve oil pressure in an older, high-mileage engine. The slightly thicker oil film from the heavier base weight oil — 10W — can help protect worn engine bearings as well.

Can you mix Mobil 1 with mobil1 high mileage?

Yes. Mobil 1 is fully compatible with conventional motor oils, semi‐synthetic motor oils and other synthetic motor oils, should it be necessary to mix them. But the superior performance of Mobil 1 will be reduced by diluting it.

Is mixing different motor oil bad?

Since motor oils are generally made from the same ingredients (base oil and additives), they are typically compatible when mixed. (The American Petroleum Industry actually requires that all motor oil made in the U.S. be compatible with one another.)

Will the wrong oil damage my engine?

Engine Damage

Your engine could still be susceptible to damage, and it's a good idea to have it looked at by a mechanic. Using the wrong engine oil can cause the metal parts of your engine to shear, making additional noise, and leaving metal shavings in your engine oil.

Can you go back to regular oil after using synthetic?

Synthetic oils typically provide better protection than conventional oils, but switching back and forth between full synthetic and conventional oil will not damage the engine.

Should I run a thicker oil in an older engine?

Many older, high mileage engines might face issues with oil pressure due to age and wear and tear. In this case, a practical method to improve oil pressure is to use a thicker oil, since the thicker oils have heavier base weight oil, which can help protect worn engine bearings well.

Is high mileage oil thicker or thinner?

High mileage oils contain viscosity modifiers that are durable and won't diminish over time. This causes the oil to stay thicker for longer periods of time, helping protect your engine parts.

Is Mobil 1 really full synthetic?

Mobil 1 is the umbrella branding for all of the ExxonMobil “full synthetic” gasoline engine oils.

Can Mobil 1 go 20000 miles?

Mobil 1 Extended Performance synthetic oil is recommended for oil change intervals up to 20,000 miles or one year, whichever occurs first.

Should I use Mobil 1 high mileage?

Mobil 1 High Mileage motor oils are recommended for high mileage vehicles, even those that have used lower quality conventional oils. If your engine has excessive sludge deposits due to less-than-adequate maintenance practices, Mobil 1 High Mileage can help by reducing the sludge left behind in your engine.

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