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?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?
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.
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.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.