Motor Oil Age Doesn’t Matter as Much as Mileage: Study

An oil testing laboratory has found that the conventional wisdom of six-month oil changes might be a waste of your money.

www.thedrive.com

 

Over here the intervals are one year or 15000km for the Gen6. Oil does not degenerate that quickly. After the warranty has expired: why not?

 

This topic needs lots of consideration as although oil has additives to help suspend contaminants etc the acidity of oil increases with each “short” drive cycle.

Therefore if you are doing lots of 5 to 10 mile trips each year to make up 6,000 miles your oil may be more acidic than is desired.

If you are always doing 30 mile trips each journey then the engine is properly warmed up and a lot of the acidity etc gets burnt off. This helps keep the oil in better condition.

Having said all this I am now doing less miles per year and a mixture of longer and shorter trips and I have swapped over to yearly oil changes.

Seagrass

 

The article ends with:

But for my cars? From here on out, I'm watching the odometer, not throwing away oil that's still the color of whiskey after six months.

A little over a year ago I started doing the oil changes on my brother in law's rav4. He's retired and having some physical problems. They don't drive much. The first time I changed their oil it was quite dirty - nothing scary, but obviously dirty oil. A year later I did their oil change and the oil was "the color of whiskey" - I was shocked at how clean it looked. I was ready to change their oil filter as well but since the oil was so clean I thought it wasn't warranted. It was SO clean looking that I asked if someone else had already changed their oil. Nope. It's a port injected naturally aspirated 4 cylinder, lightly used. I'm guessing they do less than 2000 miles a year.

In contrast, my 2020 Outback XT had it's first oil change within 1000 miles and the oil was black. Not crazy dirty, but it was far from "whiskey" looking. I do short trips, and with a turbocharger and direct injection, and having seen how quickly my oil turns black, I'm doing it every 6 months even if I'm only doing 2000 miles in that time. It's always dirty when I change it.

Like anything else, the devil is in the details, as @seagrass is saying. Does your oil look clean?

 

Miles is more of a factor than time. You can always send a sample into a lab for analysis.

 

I was thinking the same. Then you'll have objective data - not opinions or theories. We'd all like to know what the OP finds out if he does.

 

I'm driving only about 4K a year now and changing annually (32K on my '15). When I do run errands and such I try to group them so the engine gets fully warmed up to dissipate condensation. I change my RX-7 every 2 years, though even that hurts, since that's maybe 2 tanks of gas... Hagerty recommends 2 years for occasionally driven collector cars, so if it's OK for that $51M Ferrari GTO, it's good enough for me.

 

We have a 2021 Touring 2.5i; most of our trips are short - - 1 to 2 miles with a cold engine. With the direct injection, the oil gets fairly dirty within 6 months time, so I change it every 3,000 miles or 6 months, whichever comes first.

 

Be sure to check your Oil level at least once a month. You never want to run your car low on oil. I see you have a 2016 2.5, I have a 2018 2.5, nearly identical engine, except my CAT is different I think.

Main reason to change your oil based on time is that that the anti foaming additives in your oil quit working with time and use (mileage, short trips are much worst then long highway mileage). With foaming oil it will especially not work that well on your flat engine. The oil path in our FB engines is a bit long, you want it to flow nicely through out the path. The oil does a lot more the just provide basic lubricant for the crank and cam in our Outback.

In the motor oil we use a significant part of the "oil" is additives; they are needed. That is why some say change the oil more often, even if means using cheaper oil.

If you can DYI an oil change you can just change the oil and leave the filter alone every other oil change, if you want to save a bit of money as you would only be paying only for 5 quarts of oil; less if you would have to add a quart due to low oil level. The Oil change can be done with out jacking the Outback up.

A real good oil analysis will show the state of the oil additives. I think some of the oil analysis services out there are not good enough though for this. It is not all about wear. Lab work is an art as well as a science to do it right. I seen someone send oil to different labs and get different results. There have been a lot of oil nerds where I have lived, some later even work for major oil companies, they were obsessed with oil.

As a car gets older it needs more maintenance not less; I just about always wrongly do the contrary. I think most will say you can likely get away with only changing it once a year if you have real low mileage; more then a year never if you use it at all. Personally, I would try to change it 2 times a year on the Subaru FB engine; to many paths and the engine oil has bunch of things that it does, besides basic lubricant. Oil is cheap engines not so much.

 

Oil dilution changes everything. When my 2022 OB Premium did this, I changed the oil at 3-4000 miles or every (4) months. The oil is thin enough as delivered, thinning it down with gasoline significantly affects things in a non-positive way.

 

I looked up the Hagerty article

5 Steps to Tune-Up Your Classic Car - Hagerty Media

With an older classic car, regular maintenance of ignition parts and filters is critical. Follow these four steps to perform a basic engine tune-up.

www.hagerty.com

And for a classic car that is driven infrequently, oil change intervals should be 2000 miles or every two years.

 

I've been doing annual changes for quite a while..maybe 10 years.
My thought is motor oil is that good nowadays and engines are also better.

 

Once a year probably wouldn't do any harm. I change mine twice a year mostly for extended warranty purposes. But I also look at it from the standpoint that if I can't afford two oil changes per year I probably shouldn't own a car in the first place.

 

I have 4 vehicles I drive between 1,000 and 6,000 miles annually and I change the oil once per year. Never any problems but I don't do many really short trips. My 2004 F-150 has 59,000 miles on it.

 

Looking at my service log for my wife's 2011 Forester with the first year FB25 engine. That year has been a problem with 1st year growing problems of burning oil. It appears that I have been changing her oil every 4-5K which has been every 8-10 months. Only one time did I inadvertently extend the time to 19 months as I had some medical issues then. But even with that it was only 5,004 miles driven. I have been using Amsoil Signature 0W-20 exclusively, and I usually need to add oil at about the 3K mark. She refuses to consider getting into a new car loan as this only has 68K in 13 years of ownership.

I won't say that I am an Amsoil rooter - but the Signature Grade has performed very well in her car. I previously had owned a used 2001 GMC Sierra 3/4 Ton with the 8.1 Liter engine/Allison 1000 transmission. These big blocks were noted for being oil burners. When I first purchased it, I would need to add a quart of oil at 1100-1200 miles. But using Amsoil Signature 5W-30 oil that went to 1700-1800 miles. That was an improvement to me!

I recently sold my 2017 OB and purchased my OBW. It has been slow to work my way to 500 miles for me doing its first oil change! My plan is to change it again at approximately 3000 miles and then to the dealer at 6000. I have oil sample bottles ready as I want to document the life as it is probably my last car. The next time I change the oil in my wife's Forester I will take a sample too. For that car, I want to check for coolant in the oil besides the overall engine condition. Remember - she doesn't want a new car!

 

I see a lot of replies where people say to visually examine the oil but I find this method to be not reliable. To me, old oil ALWAYS looks dark when I do an oil change no matter the interval. It does not necessary look dirty but just dark. So, I guess the only way for me to know for sure would be to send a sample to the lab.

One of the reasons I started questioning 6-month intervals for my Outback is because of my other vehicle - Jeep Cherokee. In the manual for my Jeep Cherokee, it says to change the oil either based on oil life indicator OR to change it every 12 months if oil life is still above 0%. With that being said, I probably put about 5k miles on my Jeep Cherokee every year and every time I do an oil change once a year my oil life is still about 50%.

I will probably just start changing oil on my Outback every 9-10 months. I must say though that I do a lot of short trips.

 

Some engines run cleaner than others. You don't have a turbo or direct injection so for you, intervals shouldn't be as critical as it would be for that kind of engine. My brother in law's engine is more like yours but my engine is way more demanding on the oil. His oil looked practically new. Seriously it was clear amber, and I had filled it with Costco synthetic oil - nothing special.

 

Good to know about turbo and direct injection engines. Thank you.

So years ago there was a gentleman who claimed his Outback was burning oil until he switched to using only the Subaru's motor oil. I have been using ONLY the Subaru's motor oil because of this reason, although I feel tempted to try Costco's in the future when I buy a new vehicle.