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2010 Forester XT
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16 Posts
Discussion Starter #1
Not to continue the conventional versus synthetic debate, but I wanted to pass on a piece of info SoA told me yesterday when I called in.

My owner's manual didn't recommend synthetic for turbos (only saying you could use it if you want), and there didn't seem to be a consensus on this board either, so I was confused as to what to use.

I spoke with two reps at the SoA line (I had to call back because I forgot a few questions) and they both told me the same thing--the tests Subaru has conducted (or Fuji I guess?) show that there is no difference between synthetic and conventional on turbo engines in terms of performance or longevity. They said the testing shows that the true concern lies in the frequency which the oil/filter is changed (3,750 miles or ~4 months). That being said, they both recommended conventional since the tests found no performance or longevity difference.

I know little to nothing about oil, and I'm not sure whether to take the tests and advice with a grain of salt, but I wanted to put it out there.
 

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Administrator
2007 Forester Sports XT 4EAT
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40,088 Posts
I split the difference & use Valvoline MaxLife 5W-30 in all my vehicles. It's a synthetic blend. In addition, I don't extend the oil & filter change past 3K mikes. :wink:

Bobby...

['07 FSXT MODding Journal] ['03 X MODding Journal]
 

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2009 Forester XT 4EAT
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2,265 Posts
It really comes down to a personal preference. I use full synthetic and change at 4000 miles instead of 3750 (who was the rocket scientist that came up with THAT odd number). It might be overkill, but I don't drive that many miles and when I do I tend to play a lot.
Again, my personal preference as others have theirs.
Decide what you are comfortable with and go for it. :biggrin:
 

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2010 Forester XT
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16 Posts
Discussion Starter #5
In regards to the testing, that's correct--the stock 2.5 turbo engine.

The other thing they told me was to check the oil regularly to see if any needs to be added. Is it all that common to need to add more oil on the turbos in between changes, or is it fairly rare? I had an Accord for 100k miles and it never was low in between changes (granted, it wasn't a turbo).
 

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2010 Forester XT
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Discussion Starter #6
It really comes down to a personal preference. I use full synthetic and change at 4000 miles instead of 3750 (who was the rocket scientist that came up with THAT odd number).
Haha! Yes, I was wondering the same about the 3,750! A 4,000 mile interval or even a 3,500 would be easier to keep track of.
 

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2009 Forester XT 4EAT
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2,265 Posts
In regards to the testing, that's correct--the stock 2.5 turbo engine.

The other thing they told me was to check the oil regularly to see if any needs to be added. Is it all that common to need to add more oil on the turbos in between changes, or is it fairly rare? I had an Accord for 100k miles and it never was low in between changes (granted, it wasn't a turbo).
At 29K mine still has yet to have used one drop of oil between changes. A major benefit of checking the oil each time I fill up is that I have a good idea how my Foz is running between oil changes. I can easily notice if the oil is getting black early as well as other things like low coolant, low brake fluid or if the trans fluid is starting to smell. It takes maybe a minute while I fill the tank...to me it's worth it.
 

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2004 fxt A/T
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2,567 Posts
Of course conventional and synthetic will perform the same on a less than 4k interval. The entire point of using a synthetic is the extended interval and it doesn't sheer to a lighter weight. That is like saying a framing hammer and a sledge hammer both broke the window on the first swing, therefore they are both the same.
 

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2010 FXT Limited Auto
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33 Posts
Haha! Yes, I was wondering the same about the 3,750! A 4,000 mile interval or even a 3,500 would be easier to keep track of.
Service intervals are based off a 15k/yr interval which gives you 3750 every 3 months. The thing that stumps me is why do automotive companies plan their maintenance around 15k/yr yet have warranties based on only 12k/yr.
 

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The Sub kit guy
2005 Forester X & XT VF39
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13,008 Posts
Haha! Yes, I was wondering the same about the 3,750! A 4,000 mile interval or even a 3,500 would be easier to keep track of.
3750 fits in with the regular maintenance plan and falls in nicely with 7500, 15,000, 30,000 etc.
 

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'09 STI
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4,128 Posts
adam5800 said:
Is it all that common to need to add more oil on the turbos in between changes, or is it fairly rare?
If you accelerate/decelerate a lot at high RPMs and see high g forces in the turns, yes.

If you follow Subaru's change interval on the XT all you're doing is wasting money using anything other than plain old oil...
 

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2009 Forester XT Limited
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376 Posts
If you accelerate/decelerate a lot at high RPMs and see high g forces in the turns, yes.

If you follow Subaru's change interval on the XT all you're doing is wasting money using anything other than plain old oil...
I would tend to agree and although I have no scientific data to back it up, I feel pretty confident in the conventional oils at a 3750 interval, however I will also change the filter every time as well whether that's "recommended" or not to make sure I am "starting over" with each oil change.
 

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2004 Forester XT 5MT
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292 Posts
My Old High-Reving 4AGE used Catrol GTX High-Mileage at 250K miles and still runs strong. Always changed oil at 3,000 miles or less.

I did notice when it comes to conventional oils " Catrol GTX High-Mileage " burned alot less than Valvoline. When using Valvaline I would have to add a half quart at 2K miles. Plus at Walmart the 1 gallon is alot cheaper than Kragen, pepboys, autozone, ect.
 

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99 UK S-turbo
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the tests Subaru has conducted (or Fuji I guess?) show that there is no difference between synthetic and conventional on turbo engines in terms of performance or longevity.
Subaru will of course test worst case, and of course you can't assume all synthetic are the same as all others, but like for like synthetic oils DO last longer than non syth, especailly those designed for the latest long service intervals (such as the latest VAG 2.0 turbo's with 25,000 mile interval).

Simon
 

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2009 Forester XT Auto
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218 Posts
Personally I prefer the high temp, shear stable formula a synthetic offers over conventional. I don't see why you would want to run conventional in a turbocharged car even though according to SofA you can.

I used GC 0w30 and it felt ok, I used conventional a couple of times but it felt a little harsh in high rpm. I am now dead set on running Rotella T6 5w40, engine feels smooth as butter and with a tune I'd want a slightly heavier weight so is doesn't thin out when I am romping on it.

I plan on sampling at 5k miles and seeing what Blackstone has to say.
 

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07 FXT
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828 Posts
Oil Analysis

Mostly out of curiosity I had an oil analysis done with Blackstone Labs. If you don't know, they will analyze a sample of your oil for about $25 (I think). They can tell if you have fuel or antifreeze in there (bad) or excessive levels of different metals (indicating abnormal wear).

My car: 07 XT, modded to 280 whp, 44,000 miles, running Mobil 1 10/30.

Sent in a sample taken at 5,300 miles. they said it looked good, suggested I could try 7,000 miles. Not sure I will ever go that long, but it is nice to know I could if I happen to forget and run a little longer than usual.


Greg
 
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