2.5 NA Used Oil Analysis

[sixfifty]

trace fuel is pretty good. my uoa have shown a wide variety of readings, varying by the driving style for that period (stop and go or freeway). they aren't even showing a number (although maybe they've stopped showing numbers for low amounts).

tbn is dicey, since it can be measured multiple times and give different results. probably good not to press that oil further under similar conditions.

all in all, a decent uoa.

[bulwnkl]

Though I'm late to the party, I thought you all would be interested in this:

Blackstone isn't looking for fuel directly. They simply measure open-cup flash point, and calculate a fuel content number from there. So there's no need to waste brain cycles on number of carbons in this molecule or that; they're not looking that closely.

Also, Blackstone's TBN measurement method is different than many, and so a TBN of 1 is their typical condemnation point, whereas other labs/methods will usually have a higher number for their condemnation point.

[Bimmer]

Originally Posted by sixfifty

all in all, a decent uoa.

Originally Posted by bulwnkl

So there's no need to waste brain cycles on number of carbons in this molecule or that...

Yeah, I'm not really worried about it. The oil is gone, anyway, so there's not much to do, anyway.

Originally Posted by bulwnkl

Also, Blackstone's TBN measurement method is different than many, and so a TBN of 1 is their typical condemnation point, whereas other labs/methods will usually have a higher number for their condemnation point.

Right, but seeing as my oil was at 1.6, I think it would be really pushing it to go another 1,000 miles on the next OIC in hopes of getting it all the way down to 1.0!

[the evil twin]

Originally Posted by Bimmer

Right, but seeing as my oil was at 1.6, I think it would be really pushing it to go another 1,000 miles on the next OIC in hopes of getting it all the way down to 1.0!

What oil were you using? TBN was 1.6, that seems low. After nearly 4000 miles, including towing, mine was over 5: 3.6r UOA @ 4000 miles

[Bimmer]

Originally Posted by the evil twin

What oil were you using?

The cheapest 10w-40 I could find.

It's verrry possible that Chevron or Shell or whoever made it skimped on the additive package.

Of course, I also ran mine almost 6,000 miles, and over two years...

[mcbrew]

I find it interesting that you are using the cheapest oil, but will pay for analysis. What about using a higher end oil in there? I put a true synthetic in all of my vehicles... usually Amsoil or Redline. Yes, they run about $10/qt, but that's only about $25 more per oil change than cheap stuff... and it lasts a lot longer. I haven't sent any of the OB's oil out to Blackstone, but in my Scion xD, the Redline oil was still good at 12,000 miles... and that includes towing my camper and cargo trailer quite often! I decided on a 10,000 miles OCI because it was easy to remember.

[Bimmer]

Originally Posted by mcbrew

I find it interesting that you are using the cheapest oil, but will pay for analysis. What about using a higher end oil in there?

You're completely right, of course...

Basically, I had always run dino oils, just whatever met the SAE spec and was on sale...
Then I wound up with the XT, and heard about all the oil related problems, and read up on oil, and decided to upgrade.

In the meantime, of course, I still had the remainder of a case of basic 10w-40 laying around, and I'm too stingy not to use it in the Impreza (and as others have pointed out, these NA engines rarely have oil-related problems).

FWIW, I first put some leftover Rotella 5w-40 in the Impreza, and then topped it off with the old 10w-40...

[TooSlick]

If you're using Blackstone Labs, I'd change the oil when the TBN reaches 25% of its original value. For other labs such as Oil Analyzers, I'd change at 33% of the baseline TBN.

It's common for a petroleum based, SAE 10w-40 to shear down to a lower viscosity, since it uses a fair amount of polymeric thickener (VI Modifier).

FWIW, I think that BS Labs tends to under predict actual fuel dilution....

TS

[Bimmer]

Originally Posted by TooSlick

If you're using Blackstone Labs, I'd change the oil when the TBN reaches 25% of its original value. For other labs such as Oil Analyzers, I'd change at 33% of the baseline TBN.

Dumb question, but how do you figure out the "baseline" TBN, without sending in a sample?

[AWDFTW]

Virgin Oil Analysis.

PQIA has a lot of oils that have their samples published.