Some possibly dumb questions about Subaru turbos

[dvancleve]

Howdy folks,

I've been reading BITOG for quite a while now. I drive a 2007 Outback XT turbo, I believe the last year with the 7500 mile OCI and a variety of viscosities listed as acceptable. I'm not sure if it was 2008, but I know Subaru went to a 3750 mile OCI and specified 5W30 oil. At some point after that, they specified synthetic 5W-30 oil. I am aware of the turbo life span concerns and know about the turbo banjo bolt oil screen. Mine is at about 70,000 miles and was run on mostly dino 5W30 ffor the first 55(ish)K miles, but always had oil changes at the appropriate times. I'm well aware that 5W40 synthetics are the preferred oil in these, outside of warranty concerns. I also recognize that changing even full synthetic out every 3750 miles is cheap compared to the price of the turbo and most of he time my driving only results in fewer than 2 oil changes per year. I haven't done it yet, but I'm probably going to remove the turbo side banjo bolt screen. Full flow of any oil is better than not enough due to clogging…

All that said, I have a bunch of questions. It seems to me like the order of some of these changes is questionable... The 3750 mile OCI was presumably to make sure that dino 5W30 wasn't breaking down too much before it was changed. It seems like specifying synthetic was also addressing that same issue, perhaps even in 3750 miles dino 5W30 was breaking down too much? Going to a 5W40 HDEO or a euro spec 0W30 or 0W40 seems like it should address any kind of shearing Issue, so what about the 3750 mile OCI? Oils I've purchased for this car, based mostly on BITOG, are PU 5W-30, Mobil 1 0W40 and Mobil 1 Turbo Diesel Truck (all with rebates or crazy sale prices). I also have a few jugs of PP 5W30, but those wouldn't be my preference for this car (it does have the Honda turbo rating though). Any thoughts or words of wisdom? I'm not sure I'm up for doing a bunch of UOAs, and it seems to me like those are really only valid if you're sticking to one or two oils.

Thanks, Doug

P.S. I decided to post this here rather than on one of the Subaru boards, most of the oil discussions other places seem to get pretty nutty…

 

[cptbarkey]

my rule of thumb with anything turbo subaru, replace the turbo every 100k, change the oil every 3750 like subaru says, and live life worrying about more important things.

 

[wi11iam]

~5k OCIs w/ a quality synthetic 40w oil would probably be fine. If you stick with 5w30, even synthetic I would stick to shorter OCIs however.

 

[Koz1]

From a turbo site. turborepair

This section will cover more in depth preventative maintenance, starting with one of the most overlooked parts of a turbocharger installation, the high pressure hose couplers that connect the turbocharger to the intercooler and finally the engine. Most of today’s turbo systems operate at pressures over 12 psi, so even the slightest problem with a coupler can create a leak of boost pressure. Turbochargers already operate at a high revolution speed, and any air leak after the compressor will cause the turbocharger to work even harder to overcome the pressure loss. Remember that the wastegate actuator on most turbochargers regulates the amount of exhaust energy present at the turbine wheel required to produce the shaft speed necessary to turn the compressor wheel fast enough to create boost pressure. The turbochargers wastegate is blind to the fact there could be a pressure leak, so it is going to try and force the turbo to over come this leak until the desired positive manifold pressure is obtained. This of course will create a turbocharger over speed condition, cutting the life of the turbocharger drastically.

To get started, first do a visual inspection of all the hoses, clamps and tubes. Look for signs of a pressure leak, such as damp or oily residue around the hose or clamp, bulges or soft spots in the hose, rubbing against another object that could cause abrasions or tears and finally inspect the intercooler core if equipped for indications of impact from gravel or other objects thrown up from the road. Repairs can be as simple as tightening or repositioning a hose or clamp, to replacing torn or damaged couplers.

If your car has over 100,000 miles on the odometer, it is advisable to remove the intercooler and piping, thoroughly cleaning the entire system to remove oil residue and check for any problems. If you have the equipment, pressure testing the intercooler system by making a pressure plug for the front of the turbocharger and applying pressure to the system while it is installed on the car will provide the ultimate way of knowing your system is sealed and functioning properly.

The next item of inspection for the high mileage car will be the oil supply line. Over time this line is subjected to oil flow and of course temperature extremes. The oil will start to turn to carbon in the areas of high heat, and if left un treated can create a detrimental restriction of oil flow to the turbocharger itself. Usually oil supply lines are relatively inexpensive from the dealership, and if your car has over 100,000 miles showing, the line needs to be serviced. Note that this line cannot be reliably cleaned, replacement is the only safe way to complete this job.

While you are servicing the high pressure oil feed line, take the time to inspect all of the oil return line gaskets and connections. Although it is a very important line, cleaning and re-installing is often the only maintenance needed, there is no need to replace the line with a new one unless it is damaged beyond service. The same will also hold true for the turbocharger coolant lines, if equipped.

One question we get asked a lot is how to do a visual inspection of the turbocharger itself. First off, you will need to gain access to the turbochargers compressor inlet. Once you can see the compressor wheel through the inlet opening, observe the area for an excessive amount of oil present in the inlet, or on the compressor wheel itself. The wheel should be a natural aluminum color, with no signs of impact damage or contact with the compressor housing. If it is possible to spin the turbocharger with your fingers, note any resistance or noises. The turbocharger should spin freely, with no rubbing, scraping or other unusual sounds. The turbocharger will have small amounts of radial (side to side) movement in the bearings, but it should never be able to make contact with the compressor housing inlet. Your turbo should have no noticeable axial (in and out) motion that you can feel. If any of these diagnosis fail to pass inspection, the turbocharger needs to be serviced immediately.

 

[scurvy]

I would do two back-to-back 5k oil changes with M1 5w30, M1 5w40 TDT or Shell Rotella T6, then start UOAs at 5k on the 3rd oil change to see how long you can take it.

 

[Bandito440]

Yep, 5,000 miles is generally appropriate as long as you're not modifying or racing these.

Stop using 5w-30 and jump up to 0w- or 5w-40 synthetics.

Rotella, Mobil 1, Castrol; all good choices.

 

[Bandito440]

Rotella T6 can be had for pretty cheap at the moment. Pick up two gallons to start.

 

[Greasymechtech]

Stick with synth. 2 oil changes a year is fine if your commute is less than 15k a year. Top off oil as needed.

Stick with the 5w40, 0w40, 10w40, or euro 30 grades.

I also wouldn't fear the 5w30 that you have. Use it during the winter...if there is one.

 

[A_Harman]

Pennzoil Ultra Euro 5w40.

 

[FutureDoc]

Not a turbo-ed Subie driver but... HDEO does have a cult following with boosted engines. I think a lot of the "nutty" part is partially due to how flogged these engines can be driven. And they are flogged cold. A quality 5w30 will be "ok" if you keep the RPMs low/reasonable with reasonable OCI but if you are spirited, then a 10w40 or 5w40 is not a bad idea. (Heck, you can hunt down 5w30 HDEO if you are worried). However, in AZ, yeah a Xw40 is not a bad idea.

For me, I have 10w40 mix T5 in my NA EJ25. Can't complain.

 

[skyactiv]

I owned an 07' WRX I bought new and sold with 136K on it. I have some UOA's posted on here. The only issue I had with my car was the clutch slave cylinder going out. I went to a Perrin map stage 2 tune around 61K and my car did mid 13's in the 1/4 mile. I ran mostly Valvoline Synpower 5W30 at 4K intervals. There is a guy on Nasioc that needs to swallow a Xanax anytime WRX and 5W30 is mentioned in the same paragraph.

 

[rjundi]

I own the similar car a 2005 Legacy GT wagon manual transmission with same motor.

I stuck to 4k intervals with dino 5w30 and have had trouble free operation for 181,000 miles related to oil. It did however burn a valve(171k) and the engine internals and turbo were inspected and in exceptional condition. The banjo bolt was pretty clean and changed then too.

I got a letter reverting OCI to 3750 I think in 2007ish and stuck with it. Not sure if I would exceed 5k with any oil with this motor. Forums are laden with all sorts of major failures of this motor that touch oil. I'd be leary of extended.

Remember to check this engine for oil. Ours starting consuming about a quart every 3.5k at 170k where before not a drop.

My wife is the main driver and our car rarely exceeds 4500 RPM(peak torque) with her driving but car is going 70-80MPH in her commute.

 

[bluesubie]

Different car, same engine.

At around 82k miles, I had turbo failure on an OEM turbo with only 20k miles on it, likely due to pushing the OCI to 7,500+ miles on 5W30. It had high detergency but a low-ish HTHS. That was actually the only time that I ran an oil with an HTHS of less than 3.5 since around 2004.

The head tech at my dealer said that it was a lubrication related failure due to a clogged banjo bolt screen (the one near the turbo) although there was no sludge. That turbo had only 20k on it because my original turbo was replaced at 60k due to excessive oil getting past the seals.

I asked the tech about removing the screens but he advised against it because he felt the benefits outweighed the negatives (blocking debris). Since that time, I've stuck with non Resource Conserving oils changed at 5-6k intervals.

Less than a year ago, I had to get a valve job at around 130k miles due to a burnt exhaust valve. the dealer used Subaru 5W30 after that work and I changed it at 3k. It was 2007/2008 when SoA switched to the 3,750 mile interval and 5W40 was allowed up until the 2011 model year. There was no change to the engine (although the screens were removed a few years before that) when they dropped 5W40. Likely due to CAFE.

SoA did switch to 7,500 mile OCI's after they began "requiring synthetic" although they just cut that back to 6,000 miles/3k miles for severe service. As of 2011, turbos were not automatically considered severe service any longer although I wouldn't be surprised if the oil diluting DIT engines change that.

I've now cut my OCI's back to 5k miles.

-Dennis

 

[fdcg27]

Originally Posted By: cptbarkey
my rule of thumb with anything turbo subaru, replace the turbo every 100k, change the oil every 3750 like subaru says, and live life worrying about more important things.


How many turbo Subies have you owned in developing this rule of thumb?

 

[cptbarkey]

Originally Posted By: fdcg27
Originally Posted By: cptbarkey
my rule of thumb with anything turbo subaru, replace the turbo every 100k, change the oil every 3750 like subaru says, and live life worrying about more important things.


How many turbo Subies have you owned in developing this rule of thumb?


more then you should be concerned about, but i never discourage someone from asking a question.

 

[fdcg27]

You should try giving an answer, then.
My "concern" was that you were merely spitballing with no basis whatever.

 

[cptbarkey]

Originally Posted By: fdcg27
You should try giving an answer, then.
My "concern" was that you were merely spitballing with no basis whatever.


how about contributing to the thread instead?

 

[fdcg27]

Okay, I will.
Turbo Subies are typically fine with synthetic forty weight oils changed on 5K intervals.
The turbo will often last the life of the car.
Subaru has been making these things for decades now.
They know what it takes to make them work.
I currently own two NA Subraus.
You?

 

[cptbarkey]

Originally Posted By: fdcg27
Okay, I will.
Turbo Subies are typically fine with synthetic forty weight oils changed on 5K intervals.
The turbo will often last the life of the car.
Subaru has been making these things for decades now.
They know what it takes to make them work.
I currently own two NA Subraus.
You?


1999 subaru forester, replaced the head gaskets, steering rack, amongst other items that i cant recall. she's had it for 3 years and the catalytic converter is starting to plug up but otherwise its fine.

1998 subaru forester for parts, repaired upper vehicle with some of it. scrapped it to a junkyard when i was done with it.

1997 subaru legacy 5mt 2.2l, replaced the clutch, used an ozone machine to attempt to get rid of smoke smell, worked somewhat, replaced other various bits on it, sold to a nice local guy.

bought a JDM EJ25D from ebay, replaced the head gaskets, never used it, sold to a guy a couple hundred miles to the south.

2004 subaru forester xt with a blown auto transmission, fixed it, repainted it, sold it to a nice washington state transplant.

2005 subaru legacy gt, blown turbo, replaced it and a few other bits, flipped it to a jerk who had buyers remorse but tough luck pal.

2012 subaru outback cvt, great highway cruiser, sold it after a little over 1 year because i was bored with it.

in my judgement my after quite a bit of amateur research and hands on experience on my part has told me that subaru turbo's explode after 100k. however they are a joy to work on. if your interested in more just google my forum name, you'll see it all over the place asking for humble help. i feel famous now, thanks for asking nicely.

 

[bulwnkl]

I found that RLI 5W40HD was significantly superior to everything else, including other RLI fluids. Nothing else resisted fuel as well, nor returned as good mpg, nor could match it for low oil consumption, nor could match its wear rates in my last turbo Subie, an '05 Baja.