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2015 Forester Premium
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Discussion Starter #1
Irridium plugs. Dealer says 60K miles. NGK says 100K miles. What say you?

Synthetic 0-20 oil change interval. Dealer says 6K miles. Owner's manual says 7.5K miles. What say you?

Had a really interesting conversation with a former service manager that has his own shop. He kept asking "Is it running bad?" In reference to various "Do I need this?" type of questions.

He suggested waiting on brake pads until it made noise. Those noisemakers. ;) Then jumping on it.

Was adamant about doing the timing belt when it was due.

I do lots of highway miles. So that might be easier on things. I could use some opinions. :)

Thanks in advance.
 

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Sahuarita, Arizona USA 2018 Forester Limited
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Subaru, the manufacturer, recommends spark plug change at 60K so I would go with that.

I have the same engine in my 2018 and my owners manual recommends oil change interval of 6K miles. If Subaru changed the recommendation from 7.5K to 6K on the 2015's there must have been a reason.

Your 2015 does not have a timing belt. Find another mechanic who knows your car.
 

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1999 A/T - 235,000 mi. WA state
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Brakes, when you rotate your tires, or get new tires, ask the tire shop to check the brake pads. They'll catch the pad wear early.

Oil interval: you can't damage your engine by changing your oil too often. And it's cheap.

Iridium plugs: use em until they start to miss or you're having other work done down there.
Iridium plugs are a lifetime purchase for some owners. Mileage guess: a lot more than 100,000.
 

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2017 Touring CVT
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UhOh--About plugs--over the years I've bought more than a few used cars including Subs with pretty high mileage and have changed plugs soon after purchase. Often there's hardly any electrode left and yet the cars ran without any obvious problem, so I've come around to your recommendation as well.
 

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2012 Forester X 5 MT
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I suspect the OCI was dropped to 6K because of the oil burning problem. Subaru was afraid of people not checking their oil and running low.

Unless you do short trips with insufficient warmup, full synthetic oil will last way longer than 6K (IMO). But...as they say, oil is cheap so do what lets you sleep at night.

I will change my iridium plugs when the MPG starts to ease off. I expect that will be at least 100K.
 

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2014 Forester 2.5i CVT
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The OCI on my 2014 NA is 7,500 miles. Subaru reduced that to 6,000 for later model years starting with, I think, 2015, though the engines are identical.

As another poster mentioned, it is common belief that the reduction was due to concerns over some of the engines burning oil, hence running out of oil. Not that a 7,500 mile OCI is too long for today's synthetic oils.

I continue to use 7,500 as the OCI for my 2014. 48,000 miles on the clock. Mine is not an oil burner. However, I would recommend you stick with the Subaru recommended OCI for your model year.

So, are the factory spark plugs iridium? If so, I'd be real tempted to go 100k. I know my wife's former 2009 Honda with iridium plugs went 100k before I changed them per the owners manual. They looked almost new. I'll be facing this decision myself soon. It's not cheap to have the shop change the plugs on a Subaru, and for good reason - It is a bear to get to them. I likely will attempt it myself. But I know I'll have to buy a few small tools and block off a full day to be on the safe side ...
 

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Discussion Starter #8
Owners manual says 7.5K on the oil change. Chart says Irridium plugs.

So if I don't have a timing belt what do I have in there? My car was nowhere near this guy, but that would be a valid concern I suppose. Hard to find a 1 man shop that only works on Soobs here.
 

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2018 Forester 2.5iLimited CVT
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According to my dealer, they do come with Iridium plugs. Have about 85K on mine and will make an appointment soon to have them changed. I really believe 60K is too soon to have them changed. They probably will go 100K
 

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Discussion Starter #10
They changed the recommendation on oil changes at one point. I haven't change my plugs but will be looking into it in the spring.

2015 Subaru maintenance schedule and new car break-in period
This is great chart thank you. I see I have a timing chain. That is good. Hope those gaskets last forever, too.

Follow up question. Back in the day we referred to highway miles as easy miles. As in easy on machinery.

Does this still hold true within reason? I don't tarry, nor am I bashful about using my brakes. But I tend to put it at speed and stay there.
 

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2015 XT Premium CVT
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At 100k I am going to change my plugs, CVT fluid, brake fluid and coolant which will be in the spring. Originally I was going to get a new car but decided to keep my XTP.
 

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2014 Forester 2.5i CVT
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When you change plugs, do you change wires? Enquiring minds want to know. ;)
Surprise! Your 2015 has no spark plug wires! Each cylinder has its own coil that is combined with a "boot" that sits right on the spark plug and is screwed to the valve cover. There is low-voltage wire with a connector that plugs into each coil pack. When replacing plugs, there is no reason to replace the coil pack unless it is damaged.
 

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2017 Touring CVT
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Even-Steve: there are a few good Youtube videos of plug changes on Foresters. I thought it was particularly interesting that removing two engine mounting bolts and lifting the engine a couple of inches gave much better access to plugs. I've been changing Legacy and Outback plugs on 2.5 engines since the mid-90s and hated it every time.
 

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Discussion Starter #16
Even-Steve: there are a few good Youtube videos of plug changes on Foresters. I thought it was particularly interesting that removing two engine mounting bolts and lifting the engine a couple of inches gave much better access to plugs. I've been changing Legacy and Outback plugs on 2.5 engines since the mid-90s and hated it every time.
This is partially why I don't begrudge the stealership $259 for 4 plugs.

The other part is I am confident they will "Make it right." If need be.

Her 18 with the nicer trim package really is a nicer vehicle. But I do like my Blooberry. :grin2:
 

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2014 Forester XT
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My 14 FXT has about 82,500 miles on it, and has never had the plugs changed yet by me or the first owner. I am planning on waiting until I'm closer to 100,000 miles and then weighing my options. Runs perfectly fine and is smooth as silk at idle when warmed up.
 

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This is partially why I don't begrudge the stealership $259 for 4 plugs.

The other part is I am confident they will "Make it right." If need be.

Her 18 with the nicer trim package really is a nicer vehicle. But I do like my Blooberry. :grin2:
If my dealer gives me that quote for replacement I will take it rather than struggling with it myself. At the same time I would probably get my differential and brake fluid flushed.
 

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2017 Forester 2.5i CVT CVT
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My 14 FXT has about 82,500 miles on it, and has never had the plugs changed yet by me or the first owner. I am planning on waiting until I'm closer to 100,000 miles and then weighing my options. Runs perfectly fine and is smooth as silk at idle when warmed up.
If your car is turbo charged, I would check the plugs.

My son had an Audi turbo and was under the impression the plugs would be changed at around 80-100K miles. When he took them out at 60K, the electrodes were almost gone. Car ran fine in this condition. Great new electronic ignitions..

Looked on Subaru's site and they recommend 60K miles for all..
 

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Discussion Starter #20
If my dealer gives me that quote for replacement I will take it rather than struggling with it myself. At the same time I would probably get my differential and brake fluid flushed.
Here is another interesting conversation around the wood stove topic. Differential oil. "When I do that, what comes out looks just like the stuff I put back in..." I actually trust this guys opinion. I had it done at 30K. On the fence about doing at 60K.
 
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