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OBW H6 VDC, Tribeca, XT6
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Why not run synthetic? There's almost no reason not to.

That being said - the perfectly maintained engine experiencing significant oil induced failure rates due to oil choices is a laughable unicorn for non-turbo Subaru's. It simply doesn't happen.

Practically speaking it doesn't matter - you can run 300,000 miles on conventional oil all day long. Never apply that to turbo's, the oil is a heat soak for the exhaust and turbo heat.

But conventional requires more frequent change intervals, and synthetic is great, cheap, and widely available and works out to the same price (more expensive but fewer change intervals), so there's almost no reason not to do it unless you like doing more oil changes or don't want to add more expensive oil on an engine using oil which presumably wont' be a 2018.

An average daily driver will have no issues with conventional oil if:
1. do not go over change intervals at all
2. do not let the oil get low
3. do not overheat the engine

Keep in mind it's less forgiving and don't neglect those things. The H6 chain tensioners aren't going to thank you if you neglect those items, rod bearings will be next.

Those items listed above are the actual oil induced failure modes of your engine that happen plenty of times. That's the important data. If you want to choose synthetic to give you a very slight edge over those issues, then by all means do it, it's great and cheap, and i'm not sure why you wouldn't do it. If you want to choose conventional and plead on mamma's grave you won't neglect those items above - you'll be fine.

there are countless H6's with hundreds of thousands of miles on conventional oil, there's not some magic thing that happens to some engines and not others or some owners and not others. "i run 300k on all my vehicles with _________________" (insert favorite boutique brand, cheapest/on sale oil, or anything in between) is common and routine - all because it doesn't matter. choice makes insignificant differences for average daily drivers.

the many thousands of Subaru's making hundreds of thousands of miles over the decades make easy quantitative practical data. many of these run conventional without issues and synthetic without issues. and then if you dial in on the ones that do have issues, which *SHOCKER ALERT* does include synthetic oil users - you'll quickly learn the causes of oil induced failures and it's never oil choices. plenty of synthetic engines are blowing up too, but it's not the oil. it's poor maintenance.

* Usually it's just owners neglecting oil changes and leaks. i can't exaggerate how common it is. i can literally buy a blown subaru engine weekly that was run low on oil. who cares what oil you use if you're going to do that?

happens.
all.
the.
time.
 

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OBW H6 VDC, Tribeca, XT6
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I suppose if you go somewhere to have your oil changed conventional vs. synthetic could be a $$ question
but if you change yourself, I haven't paid more than $20 for a jug of Mobil 1, in fact the last two were $15, it is a no brainer. Somebody always has it on sale and often there is a rebate.
I've paid as little as $1.75 a quart for it.
it's so cheap now and easy to get anywhere. and fewer changes - that's the greatest thing to me, just fewer trips and scheduling and all that jazz.

win-win-win all the way around.

unless you have a leaker/user then it may be annoying!
 

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2016 3.6R Outback
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276 Posts
Pennzoil Ultra Platinum 5W-30 is what I've run in my 2016 3.6R since 3,000 miles. You can typically you can get this oil cheap on Amazon. Make sure you always use a Subaru oil filter, or an aftermarket filter that has the bypass valve specs of the Subaru filter.
 

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2018 3.6 Outback with Eyesight, etc
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I happened to ask my Senior Service Advisor this very question the other day (conventional v. synthetic). His response which surprised me was to use conventional oil and change it every 6K miles. Said something about synthetic "thinning out," and that there was no reason to spend the extra money on a synthetic oil change. Didn't expect a dealership to suggest I spend less money.
 

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2018 Touring 3.6R
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903 Posts
To me, the main advantage to switching to synthetic is a longer service interval. However, those of us still within the warranty period should stick to the 6k interval regardless of what oil is being used. So for the majority of 3.6R owners, synthetic probably makes no sense.
 

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2016 3.6 Limited with ES
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To me, the main advantage to switching to synthetic is a longer service interval. However, those of us still within the warranty period should stick to the 6k interval regardless of what oil is being used. So for the majority of 3.6R owners, synthetic probably makes no sense.
I'm not sure Mobil agrees with you. From their site the basic 5w30 only has a 5k protection guarantee whereas their synthetic oils are much longer than that. Their basic doesn't meet the latest Dexos1G2 spec approval which is primarily geared towards timing chain wear protection.

Today I purchased 5 qts of M1 0w40 at WallyWorld for $22.97 that kicks the pants off any conventional oil on the market in terms of TBN, HTHS levels and wears the Porsche A40 approval. A3/B4 too. SN cleanliness if that floats your boat as well.

If an oil is either BMW LL-01, Porsche A40 or Dexos1Gen2 approved it's better in any spec you want to toss out in whatever daily condition one might encounter. Conventional doesn't meet those.
 
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Twilight Blue 2015 3.6R with Eyesight
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Synth if you plan on long change intervals, conventional if you plan on changing every 5k...
NEVER!!! Think you can use the once per year oil, EVER!!! That has to be the most stupid public relations debacle in history!!!
For one to honestly think they can go 12 months between oil changes is jut crazy!!!
 

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I'm not sure Mobil agrees with you. From their site the basic 5w30 only has a 5k protection guarantee whereas their synthetic oils are much longer than that.
How do you know the guarantee fairy isn't some crazy glue sniffer? -- Tommy Boy

Not many conventional oils have any stated mileage guarantee so does that mean they have no protection at all?

Mobil Super meets the API and IL standards that Subaru requires at a 6k mile interval so I will put my faith in their engineers. I've sampled plenty of my own vehicles oils over the years and have yet to see bad results on a properly running engine whether it's conventional oil at the manufacturers interval or synthetic on an extended interval. Most of these stated intervals appear to be very conservative for normal drivers.

I will probably shift to synthetic at the 2nd oil change but maintain the relatively shorter intervals for warranty preservation. If we keep this beyond the power train warranty the I'll likely bump up the interval based on sampling. This isn't rocket surgery...do an oil sample and confirm for yourself what works on your car.
 

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For one to honestly think they can go 12 months between oil changes is jut crazy!!!
The Mobil 1 annual product is capped at 20k miles and requires an extended life filter. Not sure why this seems so crazy. It's fairly well documented that there are many oils that can run that long and still protect. I've had vehicles in my biz fleet sampled at 15k mile intervals on standard synthetic and they were still well within spec.
 

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Twilight Blue 2015 3.6R with Eyesight
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The Mobil 1 annual product is capped at 20k miles and requires an extended life filter. Not sure why this seems so crazy. It's fairly well documented that there are many oils that can run that long and still protect. I've had vehicles in my biz fleet sampled at 15k mile intervals on standard synthetic and they were still well within spec.
It's not the oil, it's the filter.
And if you run 10k in a year, you might get away with it, but...
If you live in an area with drastic climate changes (Cold to hot, to cold) You really want to leave oil in your crank case that long, gathering moisture???
And please don't hit me over the head with the "Extended Use" filter...
Oil changes, even synthetic, aren't that expensive. And, while most could care less, every time I change the oil, I examine it, for possible signs of problems.
It's not that an engine can't go 12 months between oil changes, it's just not very pro active. And dn't forget, you have idiots, who put 100k on their cars in a year, and seeing such products, think they can run 12 months with no worries...
Can you imagine? A car running 100k miles on not only the same oil, but the same filter? LOL!

When it comes to oil changes, I go by millage, not time.
With me, I change my oil twice a year. Why? Because I only put around 5k every 6 months...
To many, I could go 12 months, if I used a synthetic oil, but 12k on one filter is just crazy...
But then again, I'm an old fart... :laugh:
 

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I simply cannot abide useless people.
I has wagons.
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I'm crazy.

Running M1 040 with a Wix oil filter on Mal for a 10K OCI, which is about a year for me. Old man doesn't seem to care, I might even spring for a UOA to make sure I'm not beating on him worse than the previous owner who may or may not have been aware oil actually needed changing.
 

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I’m getting seriously confused. And a bit perturbed. We have a 2013 3.6. The manual very specifically states synthetic, but the dealer has flipped back and forth between synthetic and normal. Our previous oil change was synthetic, the one before that was normal, and this one was normal. The tech had a sheet indicating normal oil for 2013 3.6s. We told him the manual said synthetic, and he referred to his sheet.

What is concerning about this is that our oil light has come on before the last 2 oil changes.

Any suggestions?
 

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I’m getting seriously confused. And a bit perturbed. We have a 2013 3.6. The manual very specifically states synthetic, but the dealer has flipped back and forth between synthetic and normal. Our previous oil change was synthetic, the one before that was normal, and this one was normal. The tech had a sheet indicating normal oil for 2013 3.6s. We told him the manual said synthetic, and he referred to his sheet.

What is concerning about this is that our oil light has come on before the last 2 oil changes.

Any suggestions?
Simple the 3.6 was designed for standard oil. In 2013 it became the only engine in the Subaru line up that was fine with standard oil or synthetic and to help dealers reduce the oil types they had to have on site they simply listed 2013 and newer subarus with synthetic oil specs.

The 3.6 is perfectly fine going either way. No big deal. Just be sure to change the oil at the proper oci point. 10,000 miles is too long wth the older engines that aren’t as clean running etc.
 

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2018 Outback 3.6R engine oil...conventional vs synthetic?

Time for my first oil change at 6,000 miles, and wondering whether to get conventional oil for about $35, or synthetic for about double the price. Anyone know the pros and cons? Does the car come with conventional off the lot? Can you switch back and forth? Can you mix the oils?
So I just bought a 2019 Outback 3.6. My dealer says that the engine "takes" conventional oil. I've not run conventional oil in any of my engines in over a decade. I live in New England and the cold starts here are no joke in the winter. Is there some reason that this 3.6 can be harmed by a full synthetic? My impulse is to push the dealer to put the synthetic in. But I don't want any bogus excuses if there is an engine warranty situation.

Any thoughts?

Thanks,

Glen
 

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So I just bought a 2019 Outback 3.6. My dealer says that the engine "takes" conventional oil. I've not run conventional oil in any of my engines in over a decade. I live in New England and the cold starts here are no joke in the winter. Is there some reason that this 3.6 can be harmed by a full synthetic? My impulse is to push the dealer to put the synthetic in. But I don't want any bogus excuses if there is an engine warranty situation.

Any thoughts?

Thanks,

Glen
Synthetic is fine... the standard prices quoted by a dealer are for their 5w30 in large quantity oil they have. They can do synthetic, it just costs more per change.
 

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2021 Outback Limited 2.5L - 🍦The Ice Cream Man🍦
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Here is what I did the other day for my Audi, which can take any 0w/5w-30/40 that meets the VW 502 oil standard:

Purchased 5 quart jug of Mobil 1 0w-40 FS Euro at Walmart for $24. Got $5 coupon for entering Hot Wheels sweepstakes. Sent in $12 rebate online.

$24 - $12 - $5 = $7 for a 5 quarts of Mobil 1

FWIW I would recommend using Mobil 1 0w-40 in any vehicle that recommends 5w-30. It is a slightly heavier oil that meets some of the highest manufacturer specifications in the world such as Mercedes Benz 229.5, Porsche A40, etc. For the price it offers a higher level of protection and performance than anything else you can use in a 3.6L Subaru engine.
 
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