Turbocharged Subaru Legacy--5,000 OCI with Synth?

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Aug 1, 2003
I have an 05 Turbo Legacy which is driven mostly on the highway along with longer local jaunts. The engine always reaches operating temperature with little stop and go driving. I have been using Mobil 1 5-30 with 5,000 OCI--I wonder if more frequent changes would prolong life of turbo, or if this is enough. Thoughts? thanks John
Easy OCI, BUT if you REALLY want to extend the life of your turbo (and the entire engine assembly) get a "turbo-timer" or the like. Cheers!
NO, you need to change the oil every 3 months or 3750 miles, whichever comes first, regardless of the oil used. Subaru is having problems with these turbocharged engines, which is why they are now mandating the shortened oil change interval on all 2008 and newer Subaru vehicles with a turbo.
What The Critic said--- new warranty requirements for Subaru turbo cars is 3750 miles. Do it, or lose the warranty. You have been warned.
Snowflaque - If you are in warranty still (bear in mind people his car is 4 years old now), and you want to maintain the warranty, then change it every 3750 miles and keep ridiculous maintenance records. Otherwise, I disagree with what others have said. Globally, this engine retains a 7500 mile oil change interval recommended by Subaru. It is only in North America where this interval has been shortened. What I would recommend you do is pick an interval and oil you are comfortable with (5000 with M1 5w30 is fine, better oils are available though) and make sure you, or a qualified mechanic, removes and inspects your banjo bolt. There is a bolt which allows oil flow from the turbo feed line to the turbo; in the middle of this bolt is a small screen filter. There is some strong evidence which suggests that early turbo failure on these cars is a result of that banjo bolt filter becoming clogged, choking off oil to the turbo. This is because it's not a maintenance item and is never checked, even though it IS a filter. Have that checked. Some people remove the filter altogether, some people clean it with solvents or fresh oil, some people replace the banjo bolt with a new bolt and filter component. Thats my recommendation :) Joe
For 3750 mile OCI's I'd probably use Mobil 1 0W-30 (only if you got the $10 rebates before they were taken down) or Quaker State Horse Power/Ultimate Durability 5W-30 (currently a $10 rebate on this as well). No sense spending more than you have to for such a short OCI.
Does the manual specify synthetic? I find it hard to believe that a synthetic oil changed 5000 miles would lead to any sort of trouble, turbo or not.
 Originally Posted By: Norm Olt
Easy OCI, BUT if you REALLY want to extend the life of your turbo (and the entire engine assembly) get a "turbo-timer" or the like.
Turbo-timers are NOT needed on Subaru turbocharged engines. June 2001 TechTIPS published by Subaru for Subaru Technicians states: "2002MY WRX TURBO COOL DOWN PROCEDURE FHI's position regarding this is that it is not necessary to perform a "cool down/idling" procedure, as was recommended with past turbo models. Our current 2.0L turbo engine has a far greater cooling capacity and, coupled with technology advances, makes this practice no longer necessary. This explains why information about cool down is not included in the 2002MY Impreza Owner's Manual. The heat contained in the turbo charger will begin to vaporize the coolant at the turbo charger after the engine is stopped. This hot vapor will then enter the coolant reservoir tank which is the highest point of the coolant system. At the same time the vapor exits the turbo charger, coolant supplied from the right bank cylinder head flows into the turbo. This action cools the turbo charger down. This process will continue until the vaporizing action in the turbo charger has stopped or cooled down."
 Originally Posted By: D189379
Does the manual specify synthetic? I find it hard to believe that a synthetic oil changed 5000 miles would lead to any sort of trouble, turbo or not.
No, synthetic oil is not required, although the use of it is allowed. Subaru does say that you're supposed to stick with the 3,750 oil change interval irregardless of the type of oil used. FWIW, I run 5,000 mile OCI's on my Stage I (ECU reflash) 2005 STi with Castrol Syntec 0W-30 with very good results.
Use a good quality syn from the beginning, with reasonable oci, and that banjo bolt filter won't clog on you imho. A good friend had a saab turbo engine failure as a result of a sludged up oil pickup screen. The car had regular 3-4k mile oci on bulk dino until the screen plugged up. I think a quality syn from birth could have avoided that scenario. Snowflaque, your current routine looks perfect.
If I'm correct he bought his car in July, 2004 and it will soon be 5 years old: although it MAY still be in the factory warranty period I'm gonna' stick with my comment that a TurboTimer (or the like) can have a very positive influence on the lifespan of both the turbo and the engine, overall. It may not be "needed" but I can't see how properly installed it would have a detrimental vs. positive effect. Maybe I'm just a "belt & suspenders" guy where turbochargers are concerned? Cheers! p.s. I doubt the 3,750 OCI requirement is retroactive to 2005 production...
If you check out some uoa's some Subaru turbo's do not perform that well with your typical Energy Conserving xW-30. Blackstone has even commented in someone's uoa that they've been seeing quite a few Subes with high copper that run Mobil1. I definitely wouldn't go past 4k without a uoa on it. I agree that you should use a quality synthetic to begin with to help avoid screens clogging in the first place. A lot of those are due to neglect or wrong oil choice. I'm running Amsoil SSO to 8k miles intervals, even though Amsoil doesn't recommend longer than 3,750 in line with Subaru (covering their butts, IMO). The only other oils that I would run that long are GC, Motul, Renewable Lubricants, or an HDEO. Rotella T is becoming a very popular choice in these cars. There's was a recent uoa posted on a modified STI using RTS. -Dennis
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