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Synthetic oil change recommendation

I have a 2014 Subaru impress with 7000 miles that I purchased in April of 2014. So when is the right time to change synthetic oil if you don’t reach the milage recommendation for an extended period of time. I have been getting conflicting information. Thank you.

Unless Subaru says you must use synthetic oil, I’d say the right time is never. What does the owner’s manual tell you about synthetic vs mineral oil?

I also hope that you follow Subaru’s recommendations about the time limit for oil changes. Manufacturers frequently tell you to change at 6 months to a year no matter the mileage.


Please don’t tell us that you have not changed the oil yet. You don’t drive much so change every 6 months and read the service schedule in your manual.


Yes I have changed the oil several times while I was still under warranty.
Since I will be out of warranty next April I wanted the actual time
required. The dealer says every 6 months or less. My manual says every 7.5
months. I wanted to know what I really should do since the synthetic oil is
much more expensive. Thanks

7.5 months is fine as long as you don’t go over the 7500 mile limit before then. Of course, you should check the oil level at regular intervals between changes to see if you need to top it off.

Your “Warranty and Maintenance Booklet” should be your guide. When in doubt, go by the book.

You are driving a vehicle that sold for quite a bit of money. The price of an oil change twice a year should not be factor. The difference between regular dino and synthetic has to be less than 50.00 a year.

I agree with Joe_Guy. 7.5 months or 7.5k miles if you use synthetic oil. For regular oil, I would do it every 3.5 months or 3.5miles.

They do that because it is easier to remember 6 month periods rather than 7.5 months. I have one that I can remember that I change in Jan and July.

6 months is a good interval, like maybe in the fall to make sure the car is ready for winter and in the spring to make sure the car is ready for summer.

No it’s not. The difference between a regular and synthetic oil change is, what, maybe $30? Less than a tank of gas. Twice a year? And how much did the car cost?

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My Toyota manual says to change oil every 5000 miles or 6 months, whichever comes first.
And that’s what I did when it was under warranty. Some of those 6 month changes were only ~2000 miles.
I drive ~5-6000 miles per year; that’s not from short trips (less than 30 minutes), it’s because I only drive typically 2-3 times per week.
I know I’ll get flack about this, now I change the oil every 5000 miles, which takes about 9 months.
If I were driving short trips every day I would still do it every 6 months.
On another forum (bobistheoilguy) there are people with “garage queens” that only get driven ~1000 miles per year, no short trips; and they change oil every 2-3 years.
My point is if the car is always driven long and far enough to drive the moisture out of the oil, but it’s driven infrequently, the time between oil changes can be extended without harm.
However, I wouldn’t do it under warranty.


I change the synthetic oil twice a year or whatever the mileage indicated was, which ever came first. That way, for high mileage cars, you get the benefit of synthetic oil.

CarTalk Lackey

The OP knows that her vehicle requires synthetic oil and does not have an oil consumption problem. I don’t see the need for those two links for her question.


Subaru Impreza - 2012 or newer. 0W20 synthetic oil required. The 7500 , 7.5 month oil change shown in the owners manual has been changed to 6000 miles or 6 months.

This is one case where the dealer is right and the manual is wrong.

I has a similar experience years ago. I had an 81 Horizon that took a Fram PH 43 oil filter, I did not know it because I never took the car back to the dealer for service, but the were having cam wear problems and changed to a PH 3416 filter (much smaller) so the oil would get to the cam quicker.

When my cam wore out I was out of warranty but Chrysler had a program where the replaced the cam on those 2.2 engines for $75.

My understanding is the new cams had a much harder surface.

I have to wonder how an oil change at 1500 miles less than 7500 or one and a half months earlier than 7.5 months would make any difference. Especially if you never go 6000 miles in 7.5 months and you’re using synthetic oil.

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I use synthetic oil in everything I own that has an engine. I change every year if the mileage doesn’t reach the change target, usually 7500 miles or whenever my truck’s oil change light comes on.

If you never get the engine fully warm, say a 20 minute drive once a month, I’d stick to the 6 months. If you are nervous about going beyond that, I’d stick with the 6 months recommended by the manufacturer - the folks that designed and built the engine.

A new engine due to oil issues costs $4500 or more. That is 45 overpriced synthetic oil changes every 6 months for 22.5 years. In my city a synthetic oil change is $50. I’ll let you do the math.

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@Marilyn_MacKenzie, you already use synthetic oil, and the car was delivered with it. The owner’s manual says to use 0W20 oil, and that has to be synthetic. Keep using the 0W20 synthetic oil.

Unless there’s a chemical engineer out there I probably won’t get anyone to agree with this but changing oil by time instead of mileage goes back to the stone age. Old habits die hard. New technology in oil formulations, especially synthetics, make it highly unlikely that oil has a shelf life. We’re not talking about a loaf of bread. Modern engines are sealed units so if a quart of oil can sit in your garage for 6 months or a year without deteriorating, why would it deteriorate in your engine? Only 3 things wear out oil before the mileage interval - short trips especially in cold weather, stop-and-go driving, and trailer hauling. 15 years ago BMW went to synthetic oil and eliminated a mileage and time interval completely, relying instead on a computer that keeps track of cold starts, stop-and-go driving, etc. Drivers under ideal driving circumstances went 25K before the “change oil now” light came on.


It’s not that oil deteriorates with time. The ‘or X months’ requirement covers the problem of many short trips, where blow-by contaminants accumulate in the oil. To get around this, oil life monitors can include all factors (miles, hours, number of starts, engine temperature) in telling the owner when to change the oil. If one’s car doesn’t have an OLM then the ‘Y miles or X months, whichever comes first’ is appropriate.

The writer for the Blackstone oil labs some time ago advertised for old oil in the original cans. He got a bunch, some of it decades old, put it in his own vehicle, then after while tested it. That old stuff was still as good as it was new. Which by comparison to newer oils may not be that great?

My 2002 Sienna is parked in McAllen. I went back in October with my Mexican Sienna, which I parked and drove the old one. Probably a few hundred miles. I am not going to be changing that Mobil-1 EP oil for a long time. If Mexico does not start complying with NAFTA and let me import that lovely old car in a couple years, I will probably get rid of it somehow. And, it will be sold with the same oil unless I change my mind.