High-mileage change concerns/experiences w/ turbo

[Stryx]

Hey all,

I've been researching for months, but am having a hard time finding 'good' information for this sort of case, so here goes my first post. The local mechanics and enthusiasts are all torn on what would be 'best' as to switching or staying conventional, but there are a few more saying just switch, then keep doing the same.

I have a 2008 WRX approaching 120k miles. It has been a daily driver with lots of highway miles early and city late with 5W30 dino (Valvoline primarily) with cheap filters. I've had no reports of oil consumption and when I check it the level always looks good (Except the one time I reluctantly pushed it to 7k around 35,000 miles!). Almost all the changes have been through a major chain that I have used for years and years.

At this point, while doing the tune-up I'm looking to upgrade the weak turbocharger as Subaru did in 09 and if I'm ever going to switch to Rotella T6/Synthetic, the time is probably now. I'm concerned with the increase in boost pressure (~12 topend now, ~19 after) and how dino oil will respond. I'm also concerned by the number of reports of people buying a new used turbo car and problems they've had when using synthetic on their first oil-change, especially with the banjo bolts. I have performed some performance logging and am comfortable nothing in the engine is too out of tolerance at this time.

When I replace the turbo, I'll also be doing the oil feed lines and related banjo bolts so if they're going to clog, now is the time. The best information I could find in a situation like mine is suggesting a 'flush' first if I'm going to make the switch, but, it seems hotly debated. I thought I would get a good oil community to weigh in if possible on if they've switched this late on a turbo car and what they know/have experienced.

This is on a 2008 Subaru Impreza WRX with an OCI: 5k on majority highway miles, 3.5 on city.

 

[147_Grain]

Doing a flush is prudent; so is Mobil 1 or Rotella T-6 in a 40-weight synthetic at shorter OCI's due to high boost, fuel dilution, and oil shearing.

 

[skyactiv]

I owned a WRX and posted my UOA's on here. I posted fanatic results using Valvoline in mine. Rotella T6 is proven in the WRX. Do the turbo on your car. IF you haven't bought an Acessport and are thinking about one, buy it from Perrin. The OTS stage two Cobb map felt horrible on my WRX. The stage 2 Perrin map was awesome. I also spent $350 getting a custom tune on an AWD dyno. It didn't feel as good as the Perrin map.

 

[tezzzas]

I use Valvoline Syn in my turbo cruiser, it has 164,000 miles. Works well for me. A flush isn't a bad idea, why not use supertech from Walmart for the flush?

 

[sicko]

A quality dino should be able to go those distances (5k), but I personally like a synthetic. However, since you're paying someone to do it, often time they rip you off on the cost of upgrading to synthetic. Do you buy the oil yourself, or do you use their oil at their prices?

Subarus have shown to like thicker oils. I feel it's worth it for you to consider something like Castrol or M1 0w-40 or Rotella T6 5w-40. Though I feel it is worth noting that Valvoline synthetic (both SynPower and MaxLife Synthetic) were the quietest and smoothest oils in my Subaru, but my Subaru is a non-turbo model.

Personally if it were my vehicle, I'd be using one of the synthetic oils I mentioned above.

I also wouldn't do a flush, there's no need for it. Conventional and synthetic oils are completely compatible with one another, so there's no reason to make sure you get every last drop of conventional out of there.

 

[Ihatetochangeoil]

I run bypass filtration, synthetic oil, and do used oil analysis. I last changed oil at 20,000 mile interval, and have lab reports that it was OK.

I don't own or run anything turbo, so I will offer no opinion on your turbo. Regarding the engine flush; however, I'm against it, based upon (Saturn TSB 99-1-08, June 1999, "Internal Engine Cleaning Products," All Saturn Vehicles).

Generally speaking, what's sauce for the goose is sauce for the gander.

I had an intake gasket leak a couple years ago that I discovered because of potassium in my oil through the stratosphere on the lab report. I got rid of it by doing three oil changes. I did the first oil change the same day I discovered the issue; ran that oil for about 2-300 miles, changed it again, did that twice. Next lab report on the oil showed potassium (an ingredient in antifreeze) as normal.

My "engine flush" was two sacrificial oil changes. I would be very cautionary purposely putting something BESIDES motor oil into the oil galleries, crankshaft oil passages, lifters, etc. How can you reasonably be sure you got all the "flushing" chemicals OUT of the motor?

BTW, my GM 3800 now has 201,XXX on it, and my UOA shows excellent. I'm hoping to do 400K on this engine.

Cheers,

 

[gathermewool]

I'm sure you realize that you can't just slap a turbo on there and call it a day. It sucks what happened to '08 owners, but it's really not that big of a deal. I've owned an '06 WRX and an '08 STI and, to be honest, I enjoyed the WRX almost as much as the STI, not to mention the better gas mileage, more comfortable ride, etc.

Instead of spending tons of money on a new turbo, tune and exhaust (if you're going to swap the turbo and tune, you might as well go full turbo-back, as well) on such an old car I'd buy a used Cobb AP for $350-450 and see how much better Stage 1 is. Then, if still not satisfied, upgrade to a DP and a Stage 2 tune.

 

[Clevy]

Originally Posted By: Ihatetochangeoil
I run bypass filtration, synthetic oil, and do used oil analysis. I last changed oil at 20,000 mile interval, and have lab reports that it was OK.

I don't own or run anything turbo, so I will offer no opinion on your turbo. Regarding the engine flush; however, I'm against it, based upon (Saturn TSB 99-1-08, June 1999, "Internal Engine Cleaning Products," All Saturn Vehicles).

Generally speaking, what's sauce for the goose is sauce for the gander.

I had an intake gasket leak a couple years ago that I discovered because of potassium in my oil through the stratosphere on the lab report. I got rid of it by doing three oil changes. I did the first oil change the same day I discovered the issue; ran that oil for about 2-300 miles, changed it again, did that twice. Next lab report on the oil showed potassium (an ingredient in antifreeze) as normal.

My "engine flush" was two sacrificial oil changes. I would be very cautionary purposely putting something BESIDES motor oil into the oil galleries, crankshaft oil passages, lifters, etc. How can you reasonably be sure you got all the "flushing" chemicals OUT of the motor?

BTW, my GM 3800 now has 201,XXX on it, and my UOA shows excellent. I'm hoping to do 400K on this engine.

Cheers,



Ha. Saturns tended to be filled with sludge,so doing a flush loosened up the mud and caused problems. I've used various different flush type products and not once ever had any type of problem.
However if it ain't broke.
Rather than a solvent type product I suggest using an ester infused oil like redline for a change or 2. It should clean anything that might be defined as deposits and zero risk.
But I see no harm in using an engine flush if used as directed.

 

[crazyoildude]

Stick with dino i have seen too many people switch to synthetic after using dino for 100,000 miles and then develop an oil leak and or oil burning. There is nothing wrong with dino. All we do at my shop is rebuild engines we see this from time to time.

 

[Stryx]

Thanks for all the input! Aside from 95% of the oil changes and some bushings, I've done the rest of the scheduled maintenance and repairs myself. I haven't botched a job yet with the the service manual,information out there, and help at times. I'm pretty confident in another 50k miles with the replacement of one other major system. Hopefully just the clutch.

The markup on the synthetic upgrade at most places seems pretty ridiculous. If I switch to synthetic I will be performing the oil changes myself for the foreseeable future. Not as big important now, but it was well worth it to me to pay something like ~$3-10 in labor for plain Valvoline and not have to deal with it.

As I've followed the situation over the years with oil and Subaru's Turbochargers I never saw much of an advantage to running synthetic while stock as Subaru advised the same OCI and got the impression they advised against synthetic in the past. I might be wrong, but, I think it was in the midst of their head gasket problems they were advising against its use?

I have my research, supporting hardware, and some good resources to be comfortable in doing a turbo install. There are plenty of reasons to address it sooner rather than later. Even though the 5k OCIs were 95% smooth highway (100-500 miles daily for several years) with rare high RPM bursts. For the last two years it has been a pretty consistent 3500 OCI. I was clueless about a lot of things turbocharging until the last few years and right now it seems pretty unclear whether I pushed the OCIs or not until I get in there.

I know the one time I pushed a 7k OCI at around 35k miles, the engine let me know its thoughts with an unhappy noise when I called for higher RPMs. I promptly took care of the situation and never got close to that again, nor heard any of those faint scary noises again. There are much better ways to get a feel for your OCI limits.

I'm not a big fan of flushes and especially not when it involves a turbo. I agree, Rotella T6 5w-40 seems a good bet for synthetics, most enthusiasts around here run it. My main concern is I have read about several instances where people immediately switched to synthetic and some problems it led to with those banjo filters mainly. It's a lot easier to mess with the banjo bolts with the turbo off, so I'd like to replace both at the same time if possible.

Without a flush, I would like to run some synthetic until I am ready to do the install or I have any sign it is acting up. Just don't want to switch and have the turbo start dying at the wrong place. As of now, the whole system runs great on inspection and logging, except a small vacuum leak on one of the intake gaskets I'll get to.

If I use a flush, I was weighing the possibility of adding something like Marvel MO or Auto-RX to the last 50-100 miles of this oil, maybe doing a cocktail at idle for a bit. Afterwards, a few very short interval of dino (

 

[bluesubie]

When you say "Subaru" advised you against using synthetic, I presume you mean the dealer and not Subaru of America. That's nonsense and SoA now advises to use synthetic in all turbos.

If you're worried about switching to synthetic at this stage, I'd try a high mileage oil like Mobil1 10W30 or 10W40 High Mileage. FWIW, Subaru actually has their own engine flush. They came out with it as an inexpensive way to deal with clogged banjo bolt screens (instead of turbo replacement) and I've heard several cases of it being successful.

-Dennis

 

[bluesubie]

Too late to edit but now I see that you said Subaru advised the same OCI and you had the impression they were against synthetic. SoA never advised against it.

 

[gathermewool]

I don't mean to digress, but what's your plan for tuning?