M1 0W-40 @ 4,341 miles; '12 Kia Optima SX (2.0T)

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Originally Posted By: Toptierpao
You are telling us that 1.5% fuel dilution will NOT sheer oil??? Ok,I respectfully disagree. Agree with you on the measurement accuracy.I have spoken to an extremely bright man with a physics degree in the oil industry who told me that those numbers can be off by 25-30% on either side.


BTW it is "shear". Sheers are a type of curtain.

And yes, I am saying that. Shear is a mechanical term and means cutting. Someone a while back posted a paper that showed some degradation of VII from fuel but IIRC it wasn't mechanical cutting like an oil that has been subjected to mechanical shearing. It was more like an inhibiting of the VII molecules to extend when hot. If this is indeed fuel dilution then it is like diluting maple syrup with water. The molecular structure of the syrup hasn't changed but the viscosity of the mixture dropped due to the addition of a lower viscosity component.

The gear driven camshafts on my old Sienna will shear the oil but I don't have fuel dilution. It is an important distinction since you may be able to do something about one of them but not the other. Or, you may not be able to do anything about either one. But knowing what is causing the viscosity degradation would be key.
 
Originally Posted By: Toptierpao
Originally Posted By: kschachn
Originally Posted By: Toptierpao
Either way the oil sheered. While not excessive,in 2 of three of his reports,there is fuel in the oil. The Hyundai/Kia GDI engines are noted for this.


No, if it was fuel then the oil was diluted with a lower viscosity material that lowered the reading.

Blackstone fuel dilution measurements have not proven to be very accurate on here.


You are telling us that 1.5% fuel dilution will NOT sheer oil??? Ok,I respectfully disagree. Agree with you on the measurement accuracy.I have spoken to an extremely bright man with a physics degree in the oil industry who told me that those numbers can be off by 25-30% on either side.


When we talk about oil "shearing" we usually are referring to a mechanical process where oil molecules are physically damaged, reducing the oil's viscosity. While maybe not technically "shearing", adding fuel dilutes the oil and also reduces its viscosity.

Blackstone infers fuel dilution based on flashpoint, which in turn is based on human observation, so there are at least two ways the measurement can go wrong. Labs like Polaris use gas chromotography that is automated and based on the actual composition of the oil sample. Gas chromotography should be lots more reliable and seems to show a dilution value substantially greater than Blackstone's method. On the other hand, Blackstone makes customers feel better...
 
Hmm. Sounds like I need to do a Polaris sampling in my near future (ideally, if I had money to burn, I'd do both BlackStone AND Polaris for a good comparison)!

VERY interesting discussion gents! I'm also curious as to how switching from M1 0W-40 (all previous oil used was the non-"FS" type) to Castrol Edge 0W-40 will turn out. Hmm...

In thinking about this, maybe I should do a two step process (yes, I'm an engineer). First, use the new "FS" M1 0W-40 oil then sample. Second, follow that with a switch to Castrol Edge 0W-40 and sample.
 
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Originally Posted By: WhizkidTN
Originally Posted By: 69GTX
Besides the 3 pt viscosity drop, the add pack has been significantly used up. Wouldn't even have guess it started off as M1 0w-40 based on that UOA.


Isn't the add pack part of the TBN value (see prior sampling)? What specifically do you look at to see if the add pack is mostly depleted? These KDM 2.0T GDI engines are known to sheer the oil down quickly. That's why I start with xW-40 oil and set my change interval to ~4K miles.


FS VOA

Non-FS VOA

Look at the values of PPM Ca, Phos, Zinc, Moly, and Boron from your sample to these other 2. I'd expect even for a UOA to remain reasonably close to those VOA PPM values....not 20-30% lower.
 
Originally Posted By: dblshock
High Ca has been associated with LSPI


If that's a concern, then most of the 0/5w-40 oils out there will have more calcium than desirable. I'd look somewhere else then. When Castrol was running their Magnesium add pack they had low calcium numbers. And Mobil 1 - 30 grades are also lower calcium/higher magnesium. I'd use one of the stout of M1 grades with hths of 3.5.
 
Originally Posted By: WhizkidTN
Hmm. Sounds like I need to do a Polaris sampling in my near future (ideally, if I had money to burn, I'd do both BlackStone AND Polaris for a good comparison)!

VERY interesting discussion gents! I'm also curious as to how switching from M1 0W-40 (all previous oil used was the non-"FS" type) to Castrol Edge 0W-40 will turn out. Hmm...

In thinking about this, maybe I should do a two step process (yes, I'm an engineer). First, use the new "FS" M1 0W-40 oil then sample. Second, follow that with a switch to Castrol Edge 0W-40 and sample.


Fwiw, Blackstone tested the oil from my DI CRV and estimated 1.0% dilution based on a 365F flashpoint (one would think your 345F would earn more than .5% more). Under substantially identical driving conditions in the same vehicle, Polaris' GC method showed dilution of >5% on several ocassions. So your dilution issue may be more of an issue than you've been lead to believe and a trip to a GC lab may be instructive.

Also, once fuel dilution occurs, like with short-tripping in cold weather, it never really goes away, even with highway driving. While we think gasoline is very volatile, large portions of it actually have high vaporization temperatures and won't "boil-off" with typical crankcase temperatures.

The whole DI/fuel dilution issue hard to get one's arms around. It's not entirely clear if it's truly harmful and some manufacturers seem to emphasize controlling it much better than others (e.g. my 2.0 na DI Ford seems to have virtually none, my 2.4 na DI Honda has tons). And we really don't know if some makers intentionally allow dilution to gain a bit of fuel economy at the expense of durability. Time will tell, I guess.
 
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