Blackstone UOA or how worried should I be?

[Husker]

TL;DR: bought a used 05 FXT last year. I've done two oil changes getting a UOA each time to check on things. Blackstone says I have higher than chromium that's most likely from the rings and sodium but no potassium so they aren't ready to call it coolant just yet. Car runs fine, doesn't have compression issues (at least it didn't when I bought it, I haven't had it tested lately), no losing coolant to parts unknown, no milkshake oil, etc. Does anyone else have insight into just how bad 5ppm chromium is?  At what point would it be a sure sign of a impending rebuild?  Not entirely sure the sodium isn't just an additive from the oil the previous owner ran still kicking around.  Two oil changes isn't really enough to flush out everything.

 

Longer version: I have an 05 Forester XT. Because I'm "that guy" I've sent a couple of used oil samples to Blackstone for analysis.  The first one came back mostly positive, the second one looks worse. It's attached.  I have some records from the previous owner indicating they ran M1 and Castrol.  With it only having two changes under it's belt with me there's probably still some of that kicking around in there.  I've also used some Genuine Subaru Oil Flush when I first got it to clean up the AVCS solenoids at a Subaru Tech's recommendation.  I did the flush myself and it did take care of the code.  The AVCS screens had already been removed.  Still, should I be frantically saving up for a rebuild at this point?  At what point does the chromium go from "that's a little unusual" to "lol what ring bro?"  I do have a little bit of coolant being lost through a rusty expansion tank near the turbo that I'm going to replace here soon, at least that's where it looks to be dribbling out.  I have none of the classic head gasket symptoms. No overheating, no mikshakes, no overflowing, no oil or sludge in the coolant, no leaks around the heads, etc.

I've also read that UOA's are pretty much only useful for determining how much longer an oil can be used and one shouldn't read too much into the wear metals or small amounts of contaminants.  People have pointed to different labs coming up with rather different metal contents for the same oil sample as reasoning behind this logic.  Example: http://www.bobistheoilguy.com/forums/ubbthreads.php/topics/3248519/1

 

Thoughts? Thanks!

[Fairtax4me]

5ppm seems pretty low if you ask me.

 

There will always be wear metals in the oil no matter what you do. You have to determine what amount of wear is normal, that way when/if those numbers rise significantly you will be able to identify a potential problem.

 

Sodium may be used in some oils as an anti-wear additive. If you search around enough there is probably some info about what additives are in the oil you currently use somewhere on the internet, likely on BITOG somewhere.

 

I wouldn't worry too much unless you start seeing some of those numbers jump up into triple or even quadruple digits.

 

You probably won't ever see oil and coolant mix if the head gaskets fail on that engine. The turbo head gaskets are what people use to fix head gasket problems on the non-turbo engines. IF for some reason you do get coolant seepage into the combustion chamber (not likely, but is the most common method of head gasket failure) the Potassium numbers will be sky high long before you ever see any mixing of coolant and oil.

[carfreak85]

You're probably fine, what did the Blackstone folks say about it?  I know they get a TON of business from the NASIOC crowd, so they should be able to compare to that population.

 

These cars tend to wear pretty well, the problem area is under the hood.  They make over 100 HP/liter (A massive number only a few short years ago), but tend to get the bare minimum of maintenance due to their humble origins.

 

This thread discusses some of the "midlife" maintenance that should be performed on this platform.

[Husker]

5ppm seems pretty low if you ask me.

 

There will always be wear metals in the oil no matter what you do. You have to determine what amount of wear is normal, that way when/if those numbers rise significantly you will be able to identify a potential problem.

 

Sodium may be used in some oils as an anti-wear additive. If you search around enough there is probably some info about what additives are in the oil you currently use somewhere on the internet, likely on BITOG somewhere.

 

I wouldn't worry too much unless you start seeing some of those numbers jump up into triple or even quadruple digits.

 

You probably won't ever see oil and coolant mix if the head gaskets fail on that engine. The turbo head gaskets are what people use to fix head gasket problems on the non-turbo engines. IF for some reason you do get coolant seepage into the combustion chamber (not likely, but is the most common method of head gasket failure) the Potassium numbers will be sky high long before you ever see any mixing of coolant and oil.

 

Yeah, I was sort of leaning that way but the way Blackston's description left me a little worried.  I realize you'll never stop wear, otherwise engines would never need rebuilding.  They just seemed alarmed by the amount of chromium.  I've sent them an email asking for some clarification.

 

As I've only done two oil changes since buying the car last year (I've only put around 8000 miles on it) I think that extra sodium is from the leftover M1 or Castrol the previous owner used still rolling around in the system.  It usually takes several oil changes with a new brand/type to competely flush out the old.  The absolute lack of potassium makes me think it's not coolant.

 

You're probably fine, what did the Blackstone folks say about it?  I know they get a TON of business from the NASIOC crowd, so they should be able to compare to that population.

 

These cars tend to wear pretty well, the problem area is under the hood.  They make over 100 HP/liter (A massive number only a few short years ago), but tend to get the bare minimum of maintenance due to their humble origins.

 

This thread discusses some of the "midlife" maintenance that should be performed on this platform.

 

I've emailed Blackstone for more clarification but their initial comments are in the report I linked above.  They seem slightly alarmed about it is the way I'd put it.

 

I'm pretty good about maintence.  I already got most of that done.  Although I tend to wait until the radiator actually needs replacing unless it's an automatic and you could get coolant/ATF mixing or I'm going on a long trip with a high mileage car.  In the past I've always caught the radiator leaking before it popped.  This FXT is a manual and usally only sees around town/country driving duty not far from home.  Although since I already have to replace that expansion tank I may just do both at once while I've got the cooling system opened up.  Turbo inlet, intercooler hose and intercooler to throttle body hose are all on the short list to get replaced this fall.  They're starting to look a bit ragged but as far as I can tell they aren't leaking yet.  Hoses, bets, idlers, valve cover seals, and plugs were all done with the timing belt/water pump right after I bought the car.  I don't like going the full 100K on the timing belt interval.  The previous owner replace the turbo and there's no shaft play (checked it myself).

 

Thanks for the info so far. 

[Husker]

Just an update, heard back from Blackstone. They'd like a sample of the Subaru Flush to see what's in it (free of charge). I might pick up some and send it in.  He said to just watch the sodium for now and see what happens.  If I do have a coolant leak it's pretty small they said but the lack of potassium make them unsure. I am pretty high on the chromium though.  Universal averages are 1, so my 5 is a little more than two standard deviations above normal so it's statistically significant. It may just be normal for this particular engine though.  I've driven it for 8000 pretty reliable miles with those numbers being that high and we only have two samples from this engine.  I may wait another year, go through another 2 oil changes and then send off a sample to Blackstone and Wix at the same time to directly compare results.  Sometimes one lab can find one thing and another can find another thing.  Or I may just quit sending in samples for a while (unless something on the car changes, starts losing coolant, etc) so I don't make myself crazy.



Thanks again, hopefully it's just nothing!

 

Edited August 12, 2015 by Husker