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Should You Use Synthetic Oil In High Mileage Cars?
Do you have a high mileage car that you are thinking about using synthetic oil in? If so you may want to know what the potential benefits and downsides can be to using synthetic oil in a high mileage car. So then should you use synthetic oil in high mileage cars? Keep reading to find out.
What Is Synthetic Oil?
Synthetic oil is a type of oil that is designed in a lab by engine oil manufacturers that is designed to help your engine be better lubricated and run more efficiently than with conventional oil. Synthetic if you did not know typically means man-made. Synthetic oil is still based on the same crude oil as conventional oil but it is designed in a lab to offer superior lubrication properties when compared to conventional oil.
What Is Conventional Oil?
Conventional oil is produced by refining crude oil to eventually produce conventional oil. Crude oil is what is mined from the ground that can eventually be refined into engine oil and gasoline. Conventional oil can still be used in most engines today if you are looking to save some money. However, synthetic oil has since been created which offers many benefits over conventional oil.
Differences Between Synthetic And Conventional Oil
Conventional oil was the standard oil used in engines for a long time up until synthetic oils were designed to help use less crude oil. The main differences between synthetic and conventional oil are the number of times that the oil is refined during the oil refinery process.
Engine oils have different grades used to inform the end-user of how refined the product is. The higher the grade the more refined the engine oil is and the better it will be at lubricating your engine. Synthetic oils typically have higher oil grades when compared to conventional oil.
Synthetic oil is superior to conventional oil mainly because it is a more purified oil that is cleaner to use in your engine. With synthetic oil, the molecules of the engine oil are similar in size whereas with conventional oil the oil molecules can vary in sizes.
This is important because the more similar in size the molecules are the less friction the oil will create while the engine is running. Synthetic oils also typically have additives added to them to help keep the inside of your engine clean and help clean any carbon deposits that may have built up over time.
Synthetic oils also flow better than conventional oil, especially at low temperatures. At low temperatures, conventional oil can start to thicken up and turn into more than a syrup than a fluid. With synthetic oil, it will consistently flow like a liquid even at low temperatures.
This means that synthetic oils are better at protecting your engine from wear especially on cold starts where your engine has not had enough time to heat up.
Is Synthetic Oil Better For High Mileage Cars?
Now that you know the differences between synthetic and high mileage oil you should now understand that synthetic oil is the better performing oil of the two. Synthetic oil can help high mileage cars by providing superior lubrication over conventional oil.
However, because synthetic oil flows better than conventional oil any current oil leaks can be exacerbated if you switch to synthetic oil from conventional oil. That’s why it’s important if you have a high mileage car that you go with a synthetic oil designed for high mileage cars as they have additives designed to prevent oil leaks.
High Mileage Synthetic Oil
With high mileage cars, your engine may be starting to wear down internally. High mileage synthetic oil is designed with specific additives to help condition the seals of your engine helping them expand. This helps with engine oil leaks that may occur from using synthetic oil in an engine that previously has not used synthetic oil.
If you have a high mileage car and want to use synthetic oil in it then your best bet is to use synthetic oil specifically designed for high mileage cars. Mobil 1 makes fully synthetic oil that is designed to be used in high mileage cars.
I’m a fan of Mobil 1 and would recommend it to someone looking to purchase high mileage synthetic oil. If you are interested in checking out the current prices of Mobil 1 high mileage engine oil on Amazon click here. Just make sure you purchase the correct oil for your engine.
If you are a fan of Castrol and would rather go with Castrol high mileage engine oil it is also a good brand of synthetic oil to go with. To check out the current prices of the above Castrol high mileage synthetic oil on Amazon click here. 
Benefits Of Using Synthetic Oil In High Mileage Cars
Using synthetic oil in your engine can help the engine last longer by providing superior lubrication when compared to conventional oil. The better lubricated the internals of your engine are the less wear the internals of your engine will be subject to.
If you use synthetic oil over the life of your engine it should help it last longer and help increase its efficiency. If your engine is already high mileage chances are you want to make it last as long as possible which is what synthetic oil is designed to do.
With synthetic oil, your engine will be better lubricated which will help it produce less friction between parts while the engine is in use. The less friction between the parts of your engine the less wear that will occur on those parts over time.
As your engine starts to wear down from friction over time this will reduce the efficiency of the engine and cause more engine blow-by between the crevices between your cylinder walls and pistons of your engine.
Overall synthetic oil is better in every way than conventional oil so it makes sense to use synthetic oil in your vehicle as long as you currently don’t have a major oil leak coming from your engine.
Downsides Of Using Synthetic Oil In High Mileage Cars
Because synthetic oil is able to flow better than conventional oil this can pose a problem if you have any sort of oil leaks coming from your engine. Any current oil leaks would only be exacerbated by replacing conventional oil with synthetic oil and you are going to end up with a larger mess to clean up on your garage floor.
If you have leaks coming from your engine and you don’t plan on replacing any engine seals to help fix that leak you are better off sticking with conventional oil. Otherwise, you are going to be constantly refilling your engine oil because it will be leaking out at a faster pace.
Another Consideration – Have You Been Using Synthetic Oil?
One other factor that you should consider when using synthetic oil in high mileage cars is has the car been using synthetic or conventional oil for the life of the engine. If you decide to switch your engine oil from conventional oil to synthetic oil you should never go back to using conventional oil as this could ruin the seals of your engine.
Once your engine is accustomed to using synthetic oil you should always use synthetic oil for your oil changes as long as you continue to own the vehicle. Synthetic oils do not cost that much more than conventional oils so it shouldn’t break the bank to keep using synthetic oil in your engine.
How Much Synthetic Oil Should I Be Adding Between Oil Changes
You should continue to monitor your engine oil levels in between oil changes to make sure that the levels are not getting too low to potentially damage your engine. If your oil level gets too low this may allow for the oil to not be able to properly lubricate the internals of your engine and allow it to cause engine wear that could be prevented as long as you maintain your engine oil levels.
Most vehicle manufacturers will say that it is normal to have to add half a quart to a quart of oil in between oil changes. If you have to keep adding more than a quart of oil to your engine in between oil changes you may want to start checking for leaks or start checking to see if there is something wrong with your engine causing it to burn more oil than it should.
When Is Your Car Considered High Mileage?
Most engine oil manufacturers say that high mileage for a car is anything over 75,000 to 100,000 miles. While that may be a high amount of mileage on your vehicle most engines today are designed to be able to run up to 200,000 miles as long as they are properly maintained.
I personally think that 100,000 miles on a vehicle are not that high of mileage especially on vehicles that are designed to be low maintenance like Toyota, Lexus, Honda, and Acura. I bought my Acura TSX with 124,000 miles on the odometer and have not had any issues with the engine even now at 190,000 miles.
The only parts that I have had to replace on my car is the alternator which you can expect to go out somewhere around 100,000 miles on any vehicle. Outside of that, I’ve only had to do normal maintenance procedures like replacing the fluids, rotors, and pads.
When I go to replace my engine oil with new oil I usually use a Mobil 1 high mileage. Mobile 1 high mileage is a fully synthetic high mileage oil. This means that it has additives within it to help protect the seals of your engine by making them expand.
If you are wanting to change your car’s oil but you have never changed your own oil before you may want to check out my other article on how to easily and safely change your oil. It details step by step what you need to do to change your own oil.
High Mileage engine oils are also designed to help reduce any sort of oil leaks caused by your engine seals and gaskets becoming brittle and shrinking over time. If you have been using synthetic oil and start to notice that your engine is leaking oil you should give switching to a high mileage engine oil a shot to see if it will help with your oil leak problem.
Sometimes all it takes is switching to a high mileage engine oil to rejuvenate your engine seals and stop your gaskets from seeping oil. One thing to note when using high mileage engine oil in your vehicle is that if you decide to use high mileage engine oil that you should continue to use high mileage engine oil while you still own the vehicle.
If you go back to using a regular full synthetic oil it may not have the same additives to help protect the seals in your engine. This can cause the gaskets and seals of your engine to reduce back to their previous size and cause your engine to start leaking large amounts of oil.
Using Synthetic Oil In High Mileage Cars- In Conclusion
Using synthetic oil in your high mileage car is ultimately up to you. I personally think it’s a good idea to use synthetic oil in an engine that is currently not leaking oil as it will help the engine last longer overall. Who doesn’t want their engine to run as long as possible?
With the comparable costs of conventional oil and synthetic oil, it makes sense to go with the superior oil. If you are unsure of how often you should change your oil in your car’s engine you may be interested to check out my other article about how often you should change your car’s oil.