2012 Legacy 3.6R - how often to change the oil?

Maintenance/Repairs
1

It’s very hard for me to get a straight answer on this, and the owners manual is vague beyond belief IMO. It says at 3,000 miles, then every 7,500 after* (with the dreaded asterisk!)… Reading on that, it goes into the normal “severe” driving with #'s of notes that only apply to certain maintenance entries.

I drive mostly highway (80%) on rural but paved routes. 4 miles of my daily commute (my own road) is occasionally dusty on dry summer days. I live in Upstate NY, so some winters get cold (much less the last few years though, I think we maybe hit 15 F, usually more like 20-30F). The 20% of driving is city stop and go for shopping, or the last mile before work…

The Manual made me think that the only applicable entry was for “extremely cold” driving. So I called Subaru to ask if they could give me a temperature that they considered “extremely cold”, because to me, that would be -10F, but what do I know what the Japanese thing is “extremely cold”. They couldn’t really give me a temp, but said that it didn’t sound “extremely cold” where I live - whatever that’s worth.

Then, out of the blue, the rep said rural dusty driving would be severe… Not in the manual entry for Oil that I could see!

The Dealer salesman said every 3,000 miles, but even the manual severe change interval is 3,750 miles… I told him he had to be wrong as the Manual, even for severe driving said every 3,750 miles…

The forums here seem to really think the manufacturers are lying about 7,500 being an appropriate oil change interval, but many seemingly trustworthy websites such as a State of California one say every 3000 is unnecessary in new engines…

I’ve always done every 3k because that’s what the shops always said, but now I really wonder if it’s not just for them to make more money. With my 3.6R, it needs more oil than is included in the $20 deals, and I’m not sure I want to regularly pay more for an oil change (anyone know what Monroe etc charge when you need 6.9 Qt Oil?)…

I’m willing to do severe changes, but I can’t see doing it more often than the manual even lists for severe driving!

2

Your described driving scenario is not severe in respect to oil. You might want to change your air filter a bit ahead of schedule, that’s all. As per when to change your oil. If the car has a turbo charger I might stick to the 3K interval, and use conventional oil. For a non turbo I’d go with changes every 5K miles.

3

You are overthinking this matter. There is no precise mileage point for oil changes. There are only vague general guidelines. The owner’s manual tries too hard to complicate matters, perhaps to cover themselves. And salesmen know even less about such matters.

Your driving does not qualify as severe. You can accept the 7500 mile interval. If you average less than 15000 miles per year, settle into a twice yearly pattern – oil changes every spring and fall.

And there is no need to return to Subaru for oil changes. Go anywhere, and keep a record.

4

The OP is correct that the specified oil change interval for that engine is 3k for the first oil change, and every 7,500 miles thereafter. I know because I have the same engine in the same model vehicle, albeit a 2011 model.

However, a factor that the OP should take into consideration with oil change intervals is the mfr’s specified interval for tire rotation, which is every 7,500 miles. Failure to rotate an AWD vehicle’s tires on a consistent basis will be…very expensive in the long run…when AWD components are damaged from running with mismatched tires. With the tire rotation schedule in mind–as well as my personal driving habits–I adhere to the 3,750 mile interval for oil changes, with the tires being rotated every second oil change. This makes for much easier record-keeping, as well as helping to prevent the build-up of damaging oil sludge in the engine. No engine ever suffered from changing the oil more frequently than the mfr specified.

Another factor that the OP should consider is the type of oil that is required. While my Owner’s Manual specifies conventional motor oil, I believe that Subaru changed their specification to synthetic oil as of the 2012 model year. If the OP’s manual does indeed specify synthetic oil, that is the only type that should be used.

As to where to go for those oil changes, I would suggest that the OP avoid Monro and all other chains–particularly those quick lube places. The number of (pick one or more) engines/transmissions/ differentials/brake hydraulic systems/cooling systems destroyed each year by quick lube places is…appalling…and the “solution” for mistakes at these places tends to be equally appalling.

My oil changes–at the dealership–cost ~$30, after the fees for hazardous waste disposal and the like are added in. And, for that $30, I know that the correct oil drain plug gasket will be used–unlike other places that likely wind up re-using the old part. The fallout of that approach can be leaks and–worst case scenario–stripped threads in the oil pan as a result of overtightening the plug. The OP should check his dealer’s website for service coupons, which can result in paying less at the dealership than at other places.

They change the oil while I wait, and if I schedule the appointment in advance, I can get a free loaner car. Try getting that from Monro! Additionally, the free “inspections” at the dealership might–at worst–result in some free repairs during the warranty period. So–there is no downside by going to the dealership (At least, at the one that I have used for the past 16 years. I have no idea about the dealerships in your area.), and potentially there is a considerable upside to going there.

5

An oil change with full synthetic for $30 is a good deal.

6

Given that your driving involves some rural dusty roads you should stick to the 3750 miles oil change interval and going that far is due to the fact that you state much of your driving is highway use.
Humidity and dust is a huge factor and what you were told about severe service is correct.

Humidity and dust is a big problem here in Oklahoma and the manual for my lawn tractor says to change the oil every 30 hours. No way is that interval going to happen because by 7 or 8 hours the oil is already nasty.

Call the Subaru parts department and ask what the over the counter price is on a 2012 long block. That will make oil changes seem cheap.

7

Not severe, 7500 is fine. And how does dust ever get into the oil, if it’s minor dust on a paved road? Modern engines are sealed, only entrance to the crankcase is tightly controlled for emissions purposes. Back when there was an oil breather on top of the engine, ok, dust might be a problem. Today, I just don’t see it.

8

I had the same recommendation with regular oil(not synthetic) for my 2005 Legacy turbo engine. I did not believe the 7500 miles so used 4000 miles instead. Guess what Subaru sent a letter to us strongly recommending the 3750 mile oil change 1.5 year latter irregardless of driving conditions. I think they paid for a few too many turbo replacements.

So now we have 140k on a 2005 Legacy turbo motor that is absolutely trouble free in with turbo and engine and running strong. We use 3750 miles.

Maybe the H6 is gentler on oil and I would use 5000 miles since its easy to remember.

9

In my opinion, for the oil, what you describe is not severe as far as either temperature or dust. I think you’d need to be driving a lot on unpaved roads for the dust to count as severe. If you’re still nervous, then go somewhere in between the two intervals, but keep in mind that changing the oil unnecessarily is bad for our planet and our country in addition to your wallet.

However, since you do have some dust, I would consider changing the air filter a little more frequently.

10

“Maybe the H6 is gentler on oil and I would use 5000 miles since its easy to remember.”

Yes, the H6 is “gentler” on oil as a result of using ~2 qts more than the 4 cylinder engines, as well as the absence of a turbocharger.

However, since the tires will need to be rotated at 7,500 miles, the owner would wind up returning to his chosen repair facility in just 2,500 miles for the tire rotation. Even though I am retired, I like to use my time productively, so I opt for the 3,750 mile interval, with tire rotation every 2nd oil change.

That interval is also pretty easy to remember, particularly since there is a little sticker on my windshield with a reminder, plus I maintain a chart of my maintenance so that I can see at a glance what has been done and what needs to be done at the next service interval.

11

Dust is an issue, crankcase ventilation or not. The reason why is that no air filter stops all of the incoming dirt and the combustion process does not vaporize all of that fine dust. Most is vaporized and out the exhaust it goes but a substantial amount will work its way around the piston rings and end up in the crankcase.

It varies, but most likely everything from 20 Microns on down will pass through the air filter and a fair number of particles larger than that will pass also.

12

I agee with Steve. You’re overthinking the matter. Your driving is not “severe use” unless you live in a hot zone (like Miami), a cold zone (like North Dakota), or a dust bowl. Highway use is not generally considered severe. Simply go with the owner’s manual recommendations, paying attention to the details that VDC pointed out. If you’re unsure whether your driving is “severe use”, simply follow the “severe use” schedule.

Don’t believe anything a salesman says. Ever. And if they really knew about cars’ mechanicals they’d be in the shop rather than on the sales floor.

The 3,000 mile oil change comes from long ago when carburated engines ran much dirtier than engines do today and oils were much more basic. Our old carburated engines ran rich (carns tend to for lots of technical reasons) and they were more sloppily put together (larger tolerances & less sophisticated manufacturing technologies). That manifested itself as more dilution and contamination of the oil. That meant more oil changes were necessary. Some old timers still remain true to the 3,000 miles philosophy, but most of us realize that today’s engines using today’s oils no longer need oil changes that frequent.

13

How much did this car cost you? How much does an oil change cost? How much is peace of mind worth to you? Don’t answer these questions here, just consider them. I believe that 7500 is ok, however I have $0 invested in your vehicle and I won’t loose any sleep over it.

14

cont

Use the recommended oil, change it at 3000, 3750, 5000, 6000 or 7500, whatever you are comfortable with. I go with 5-6000 on conventional oil and 7500 on synthetic, that has always worked for me. Saturn, 242k miles, 5-6k on conventional, Nissan PU 172k miles, Honda Accord 180k miles, Toyota Corolla 160k miles, 7500 on synthetic oil, ZERO engine problems.

15

Dust in NY is not like dust in western states. It gets dusty in MD sometimes, too, but I don’t consider my driving severe. I have almost 100,000 miles on a V6 Accord and I don’t use any oil. My change interval is 7000-7500 miles. I’d follow the book with normal change intervals. BTW, I would expect that a new Acura would have an oil life monitor. I would also follow the OLM. They have been around for more than 30 years. Honda is one of the last adapters, and they are so conservative when it comes to long life, that I’m sure they use a good algorithm for determining when to change the oil.