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We are fast approaching 300,000 miles on our 2004 Forester XT. The Turbo failed at about 160,000 miles. The engine failed at about 180,000. During these initial years, we were not very good about oil changes. Now that we have had these experiences, we faithfully change oil every 5000 miles, using Mobil Synthetic 5-20 viscosity.

I am thinking that the first turbo blew up and caused the engine to fail. I'd like to avoid that if possible. I'd like to get as much mileage as I can out of this turbo and engine.

Is there an recommended number of miles at which I should put another new turbo in, or do I have to wait until it fails?

Thanks for any information.
Curt Mason,
 

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2007 Forester Sports XT 4EAT
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I'm not sure the lifespan of your particular turbo, but given your chosen oil and change intervals, I'm surprised it isn't dead yet.

You should be using a non-MobileOne, 5w-30 (or 5w-40) oil and changing every 3000 miles. Anything more is just a gamble, and using MobileOne is basically a guarantee of failure (I know you said Mobile synthetic, which I believe is different and a much better oil).
 

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2015 Forester 2.5i CVT
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Great advice so far! Gotta add that I wish I'd kept my 2010 with 4eat transmission, CVT fluid was changed at 45k miles and it was filty dirty and smelly. Does not instill confidence in the newer Subarus. Keep what you have, maintain it better than you have been and replace the turbo before it fails and takes the engine with it. :)
 

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I'm at 260,000 KM on original turbo, tranny, etc. Still running well, burning no oil. Have used Motul 5w30 synthetic changed at 3,600 mile intervals.
 

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2014 ForesterXT CVT
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I'm not sure the lifespan of your particular turbo, but given your chosen oil and change intervals, I'm surprised it isn't dead yet.

You should be using a non-MobileOne, 5w-30 (or 5w-40) oil and changing every 3000 miles. Anything more is just a gamble, and using MobileOne is basically a guarantee of failure (I know you said Mobile synthetic, which I believe is different and a much better oil).
Where do people come up with this nonsense?

Mobil 1 oil is perfectly good for 3-5k OCI's.

"Basically a guarantee of failure" is absurd, ignorant and just plain wrong...with 3-5k OCI's.

Mobil 1 dino-v-synthetic will provide roughly the same protection(wait for it) with 3-5k OCI's.

So long as you're using the correct grade and changing the oil it'll run a long, long time under normal use. If you're the type who drops the hammer every time you come to a complete stop then obviously things change.
 

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2007 2.5XT Limited 4EAT
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[using MobileOne is basically a guarantee of failure] is this statement able to be quantified in any meaningful way? Posting hearsay and couching it as fact is exactly how all of these oil arguments start. I have been running Mobil 1 in four different turbocharged cars over a ten year span for a sum of 250,000+ miles, two of these cars being Subarus. Five turbos zero turbo failures.

A turbo should effectively last the life of the engine under normal operating conditions. Lifespan is arbitrary of course, but considering the OP got 160K out of the original with less than perfect oil change intervals this is a decent benchmark. So to answer the question of when to replace the current turbo...rough math says at least another 20K if all things are equal. At that point though the old girl will be pushing 1/3 of a million miles. Will the rest of the car be worth the repair at that point? If it were me I'd run her until she quits and give her a proper send off.
 

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In defense of Galaxywide's somewhat hyperbolic post...

Mobil1 5w30 has earned a bad reputation in the turbo Subaru community. Many WRXs have suspiciously had bearing problems while running it. (yeah, yeah, correlation does not imply causation, blah blah blah) However, most of the independent Subaru performance shops in my area decry it. It's known for shearing quickly. Rotella T6 5w40 has been a common recommendation in the past as well as Motul products.

Now, I'm just repeating what has become 'common knowledge' over on NASIOC and in the performance Subaru community. Take it for what it's worth as it's been discussed ad nauseum in every friggin' oil thread on every Subaru forum on the internet.

If you're not driving your car hard, it may be JUST FINE for you.

Now, If the OP did not make a typo, and is running Mobil1 5w20 at 5k intervals, he's asking for trouble. I'm not aware of Subaru ever speccing 5w20 for a turbo engine. Please correct me if I'm wrong.
 

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2004 forester sti
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I have nothing really to add but I use motul 300v series and the standard td 04 gets tired around a 100k and they suffer from cracking issues from memory its around the waste gate area, this doesn't always lead to lack of performance in my experience.
I was however told by Finch motorsport to stay away from Castrol, I don't know why but I listened as he has 17 years experience in formula 1.
 

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I'm not wading into the oil brand battle, but the OEM TD04 is probably a 125K mile turbo, but I'd assume OCI's have a lot to do w/that #.

And yes, a failed turbo can lead to a failed block.


AFAIK, t's the STi's VF39/43 (and 48?) that had the WG crack issue.

For the peace of mind you could pull the turbo intake or the DownPipe and see how much play is in the turbo's impeller/CHRA. Axial vs. Radial play can be a guide. Some Side-to-Side is expected; In-and-Out is bad, per my turbo background.
 

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This oil brand battle is nonsense and comparing Resource Conserving GF5 oil to an HDEO 5W40 is also nonsense.

If you’re talking API oils, brand does not matter. Mobil 1 and Castrol Edge 0W40 are both excellent choices with both oils having the Porsche A40 spec. Mobil 1 10W30 High Mileage is also ACEA A3 rated.

I’ve run all of the above oils at ~5k-6k intervals, despite still having all of my banjo bolt screens and despite having turbo failure at 82k miles. I’ve put on over another 100k since then.

I wouldn’t run a GF5 oil past 3,750 miles.
 

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My Td04 came off at 195000 miles still working fine.

Also, Mobile 1 5w30 is crap and it’s well known in the turbo Subaru community. Mobile 0w40 is a totally different animal and a true Full Synthetic.
 
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