Do you think there's a chance UOA might be ... ?

[Brons2]

I would ONLY run 8K if you were running T6 or another 5w40 that won't shear past what Pennzoil Platinum 5w30 did. Do a UOA, see what happens.

 

[kschachn]

I would ONLY run 8K if you were running T6 or another 5w40 that won't shear past what Pennzoil Platinum 5w30 did. Do a UOA, see what happens.

Where was there shearing here?

 

[gathermewool]

Where was there shearing here?

Unless I’m missing something, the OPs last OCI was using T6. It did “shear” down to a 30, but that’s likely more due to fuel dilution, if I’m not mistaken.

 

[gathermewool]

This response and your other response suggesting that you were in good shape because you were using a "W40" oil, not "W30" are baffling. Let me take one more shot at this addressing your recent questions as well as I can.

The UOA does not really determine how the oil's "performance" has held up. Oil itself, especially synthetic, holds up and maintains its physical properties for a long time beyond even 10K oci's. The oil may degrade a little, but it is more an issue that the oil takes up contaminants into suspension and in your case, fuel, into a solution. That contamination is what impacts your oil's capacity to protect the engine. In your case, there is some amount of fuel, also sabotaging the oil.

Not understanding your comment on what long intervals are for.

Synthetic oil is not doing much when your fuel dilution reaches high levels.


Change your oil at 5K.

From his previous UOA it appears that fuel dilution occurs very early. That means fuel in the oil for an extended period of time. Based on this a shorter interval is warranted.

Knowing OPs driving characteristics would be helpful.

 

[TiGeo]

The UOA isn't tell you how the oil is "holding up" beyond TBN depletion TBH. The metals bit won't vary oil to oil typically i.e. you change your oil 4x each with a different oil and the Fe and Al will likely stay the same/within the anlaytical /-. Low flash point like that in a BS UOA = more fuel then they are showing. I wouldn't run a tuned car with fuel dilution past 5K no matter what oil but honestly, yeah, with a 40W giving you some headroom to lose viscosity due to the fuel dilution (it is also most likely shearing a bit too so the drop in viscosity is a combined effect but most of it is due to the fuel - also keep in mind as the mileage goes on for an oil change interval so does oxidative thickening which counters the little bit shearing that is likely also going on if that makes sense.) With all that said, easy use 7.5K is probably fine with a quality oil. Not sure why the Subi guys all want to run Rotella (don't they call it Brotella?)...why not a Euro gasser 5W40?

 

[kschachn]

Unless I’m missing something, the OPs last OCI was using T6. It did “shear” down to a 30, but that’s likely more due to fuel dilution, if I’m not mistaken.

Yeah here it’s fuel dilution at least as far as can be determined by a Blackstone analysis. It’s just that very often a viscosity deviation is attributed to mechanical shear when there’s no definitive indication that’s the cause. The causes are different as is any possible mitigation via the oil.

It’s unfortunate that with this analysis company it’s literally impossible to distinguish the two. And it’s the most common company used by board members.

 

[gathermewool]

Yeah here it’s fuel dilution at least as far as can be determined by a Blackstone analysis. It’s just that very often a viscosity deviation is attributed to mechanical shear when there’s no definitive indication that’s the cause. The causes are different as is any possible mitigation via the oil.

I agree. I’m on board with a relatively short interval due to apparent fuel dilution, but I’m not convinced the oil can’t handle some dilution; as you allude to, how much is a mystery.