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Synthetic OIl

If I switch my car oil to synthetic, how many miles can I go before changing my oil and filter?

What does the owners manual say? That’s what you follow.

That’s because the vehicle manufacturer doesn’t care what type of oil you use, and makes no distinction between regular oil or synthetic oil.


Contrary to popular belief, the oil change interval does not change when using synthetic oil; you’re just paying for the extra protection synthetic offers.

If your car is still under warranty, you would be well advised to keep changing the oil at the intervals specified in the manufacturer’s maintenance schedule.

If the car is not under warranty, and if you don’t do mostly short-trip driving, I would say that you could safely stretch your oil changes to ~8,000 miles or 6 months, whichever comes first. Personally, I would not do that, but if you are intent on stretching out the oil change intervals, 8k/6 months is probably safe.

How many miles do you go between oil changes now?

I would not advise you to extend your oil change intervals, regardless of the type of oil you use. Use an oil that meets the specifications listed in your owner’s manual and change it as often as the maintenance schedule suggests.

I agree with VDC. I would not do it, but likely you will not cause harm by extending the changes (especially the miles) some.

Frankly, I’m a little surprised at what most people are saying here. I agree that it makes sense to stick to recommended intervals while under warranty, however, I don’t see the need to be so hesitant over longer synthetic intervals. I’ve run synthetic blends or fully synthetic oils in two vehicles, my snowmobile and plan to switch the car I currently have to it soon. I have used mostly Amsoil and trust that it’s a good quality product. I recommend going off of the recommendation of the oil/filter. At one time I used 15000 mile oil where the filter is changed halfway at 7500 miles. I have actually also used 25000 mile oil and filter. That was with a car that has nearly 200000 miles, runs great and uses very little oil. Personally, in addition to the improved lubrication, which is superior, the extended intervals is a huge advantage to synthetics. It’s a big part of what justifies the expense, that’s for sure. I understand your hesitation because everyone is told 3000 miles, no more, so hearing about extended length intervals seems crazy. I suggest you do some research and decide for yourself. Consider what kind of driving you do (highway vs. city can affect the interval you should go) and if your car goes thorugh oil. If you, for example, burn a quart or two every 3000 miles, the expense of synthetic oils may not add up for you.

When Mobil 1 first hit the market it advertised extended intervals between oil changes. However, how much to extend? People seemed to believe synthetics would last forever and soon blown motors caused a “pull back” by the mfg from the extended life claims.

I personally blew out a lawn tractor motor in 1985 assuming synthetic meant perfect oil and no worries about engine wear. Today we have very clean running motors due to pollution controls and precise computer managed ignition and fuel delievery systems. The Euro’s are taking these new factors into account and recommending very long intervals between oil changes by American standards.

I believe a quality full synthetic in a modern clean burning motor should be capable of 10K, 15K, or even 20K oil change intervals. There needs to be more science and testing done to be sure these kinds of expectations are realistic. Without the science I’m not pushing the envelope too far on my own nickel. One burned up lawn tractor was a lesson I don’t want to repeat in a T’bird, Sequoia, or Civic.

Frankly, I’m a little surprised at what most people are saying here. I agree that it makes sense to stick to recommended intervals while under warranty, however, I don’t see the need to be so hesitant over longer synthetic intervals

There are many factors involved in determining the proper oil change interval. It is very possible that a good synthetic (not all synthetics are created equal) may allow for longer change intervals, but it is also possible it will not.

Also keep in mind that different engines may have different needs.

Finally remember that there is usually a filter change with an oil change. Do you know if the recommended filter designed for fewer miles using regular oil, can provide proper filtration for longer intervals.

Oil changing is cheap enough that sticking with the original recommendations is not going to hurt. Buying a new engine will.

I am one who think you should not lock in on miles driven.They are a factor, but only one. Driving conditions and condition of motor are also important.

I think people should check their oil regularly, unless there is some reason you can have confidence in it. For example, a lot of miles on a car in highway driving, thus developing considerable experience to the point you “know” what shape the oil is in.

What I mean is get used to regularly pulling the dipstick. Don’t just check the level and put the dipstick back in. Look at the color and condition of the oil. Learn how it changes over time in your driving pattern.

For example, fresh oil may be so light it is hard to actually check the level.

Eventually, it will darken, even with normal use. If you drive a mile or two a day in cold weather, it may darken in just a few miles.

If you drive mostly highway miles, it may look fresh after thousands of miles.

It will also vary between winter and summer in the Snow Belt.

The point is look at it and try to understand what you see. If your oil darkens quickly, there is a chance you need to change more often.

There is one man who sometimes posts here who has his oil lab-tested every oil change. That is his right, but the cost is close to the cost of changing the oil and filter.

I am going to have my oil checked just once, probably in October. I use Mobil-1 extended, and assume I will be around 8,000 or more. I am doing it once because I want to see for myself in my driving pattern just how bad it gets, for future decision making information.