How Often Should You Change Your Oil?

Have you wondered how often you should change your oil on your vehicle?  Sometimes it’s not clear as to how often you should be changing your oil in your vehicle’s engine.  The key is to figure out the mileage interval that your vehicle manufacturer recommends and sticking to that.  

You would first want to find out at how many miles your vehicle manufacturer recommends replacing your engine oil.  This will typically be every 3,000-5,000 miles or once every year, whichever comes first.  

Many vehicle manufacturers will not take into account the type of engine oil used when coming up with their oil change intervals. There are also other factors that will play into how long you can go before replacing your engine oil which we will discuss below.  

What Oil Change Intervale Does Your Vehicle Manufacturer Recommend?

Once you find out at what mileage your engine oil should be changed at I would recommend sticking with that oil change interval to change out your engine oil even if you are using synthetic oil.  This is especially important if your vehicle is still under warranty.

You would want to make sure that you stick to the manufacturer oil change intervals while the vehicle is still under warranty or they may not honor that warranty.  Once your vehicle is no longer under warranty you could stretch your oil change interval longer by using a synthetic oil designed to be used annually if you wanted.  

I would still recommend changing your oil based on what your vehicle manufacturer recommends.  My car comes with an oil life indicator that will tell you how much percentage of life your oil has left in it.  I use that to judge how much longer I can go without needing to replace my engine oil and that has worked out for me.

While my car does not recommend using synthetic engine oil I use it anyway to help prolong the life of the engine.  I may be able to get longer oil change intervals when using synthetic oil but I still replace my engine oil before that indicator ever comes close to hitting 0 percent life left.  

The way I see it engine oil doesn’t really cost that much in the grand scheme of things, even if you have to replace your engine oil twice a year you should still be under 100 dollars depending on if you change your oil yourself or have a shop do it for you

Conventional Oil

Conventional oil is a type of oil that is created from crude oil that is pulled from the ground.  The crude oil is refined to eventually produce conventional oil that you can put into your engine. Because conventional oil comes from the ground it is more prone to breaking down over time than synthetic oil.  Conventional oil will also inherently contain more impurities than synthetic oil.Conventional oil used to be the main oil used in engines until the invention of synthetic oil. Because conventional oil is older technology when compared to synthetic oil conventional oil will cost less than synthetic oil to use for your next oil change.  

Conventional oil will typically have a lower change interval when compared to synthetic oil as well.  Conventional oils will typically need to be changed every 3,000 miles or so, while some synthetic oils need to be changed every 10,000 miles.  

The particles in conventional oil are not uniform in size so this will create more friction when compared to synthetic oil as synthetic oil will have oil particles that are similar in size.  This makes synthetic oil superior to conventional oil to help reduce engine wear and help your engine last longer.

Synthetic Oil

Synthetic oil was created to help get us away from using as much crude oil, to help get better emissions, and to help vehicles get better gas mileage.  Because synthetic oil is a better lubricant than conventional oil this helps engines run more efficiently and produce less heat in the process.

Excess heat is bad for engines because over time that excess heat will cause your oil to create carbon deposits that can build up in your engine.  With synthetic oil having carbon deposits build up in your engine is less likely to happen and synthetic oil is actually known to clean engines that have built up carbon deposits from conventional oil.  The main benefit for most people to use synthetic oil is going to be the oil change interval. Synthetic oils don’t need to be changed as often as conventional oils because synthetic oils are made to hold up longer.  Most synthetic oils are designed to be changed every 5,000 to 10,000 miles depending on brand and what specific synthetic oil you go with.

While synthetic oils are made in a lab not all synthetic oils are created equally.  What goes into the synthetic oil will determine how long that specific synthetic oil is designed to last inside of your engine.  Because more goes into making synthetic oil it will typically cost more than conventional oil to use in your vehicle.

The synthetic oil that I would recommend for most people would be Mobil 1 synthetic oil.  Mobil 1 synthetic oil is a full synthetic oil that they have different types of oils that are geared for different applications.  Because my car is over 100,000 miles I use Mobil 1 high mileage synthetic oil in my engine.

On high mileage engines, they may have started to wear down internally from the friction of the moving parts over time.  High mileage engine oil is designed to help lubricate the seals of your engine and make them expand to help reduce the gaps between engine parts and help prevent blowby in your engine cylinders.  

One thing to note with using high mileage engine oils is that you don’t want to go from using a high mileage engine synthetic oil back to using a regular synthetic oil as the regular synthetic oil will not contain the additives to help maintain the seals of your engine.  Once you switch to using a high mileage engine oil you should stick with using high mileage engine oils for the remainder of the life of the engine.

Semi-Synthetic Oil

Semi Synthetic oil is essentially a blend of both conventional engine oil and synthetic oil.  Semi synthetic oil allows you to get the benefits of both types of oils. With semi synthetic oil it will typically cost a bit more than conventional oil but not as much as full synthetic oil.  However, semi synthetic oil will not have as long of an oil change interval as with full synthetic oil.  This is why it is important that you check the label to see if the oil that you are looking at is a fully synthetic oil or a blend of synthetic and conventional oil.  

Personally I would just spend the extra few bucks to replace your engine oil with full synthetic oil but if you are in a pinch and need to save some money on your next oil change semi synthetic oil should perform just fine for you.

Annual/Extended Oil Changes

Mobil 1 has now created a synthetic engine oil that is designed to last up to 20,000 miles or one year.  Mobil 1 calls this Mobil 1 annual protection because you should only need to change your oil annually as long as you are not driving over 20,000 miles a year which most people don’t.  Personally, I don’t know if I would be comfortable with allowing my engine to go 20,000 miles without changing my oil.  I’m fine with replacing your engine oil once a year if you don’t drive the car that much but 20,000 miles is a long time to go without changing your oil.  

Another engine oil option is what is called extended performance engine oil.  Mobil 1 says that this engine oil only needs to be replaced every 15,000 miles or one year, whichever comes first. 

If you want to extend your oil change intervals to 15,000 miles but still want to replace your engine oil more than once a year I would recommend going with the extended performance synthetic engine oil.  

In my experience both the extended performance and the annual protection synthetic engine oil cost about the same so it’s really up to you which one you go with.

Synthetic Oil In High Mileage Engines

Because synthetic oil has smaller particles than conventional oil this can sometimes cause oil leaks if synthetic oil is used in higher mileage engines that have had conventional oil used in them for most of their lifetime.  The smaller particles will make it easier for synthetic oil to seep out from your engine in any gaskets or seals that may be worn.

I would recommend against switching to synthetic oil from conventional oil if your engine already has an oil leak as this will just accelerate the oil leak.  To learn more about if synthetic oil is right for your high mileage engine then check out my other article. If you want to be safe you could always use a semi-synthetic oil to get the benefits of both oils.

I bought my current car with 120,000 miles and started putting in synthetic oil in it from the first oil change that I needed on it.  I’ve not had any issues with oil leaks or anything like that. I do use high mileage engine oil to help protect the seals of my engine and because the engine now has 180,000 miles on it.

In Conclusion

Hopefully, now you know how often you should change your oil and the differences between conventional oil and synthetic oil.  It really all comes down to how often your vehicle manufacturer recommends that you replace your engine oil especially if your vehicle is still under warranty.  

If your vehicle is no longer under warranty you can experiment with going with longer oil change intervals as long as you are using synthetic oil.