Shearing, dilution and low cSt questions

[Flashlightboy]

I read a lot and post infrequently but this is a topic that I can't quite wrap my head around and perhaps the answer is obvious and I just don't see it.

I'm going to use PP 5/30 as an example but any other oil in the same grade with a 9 range cSt would be similar, I think.

We know that that shearing and dilution decrease the viscosity and Pennzoil, like the the others, routinely say their oil is resistant to shearing and stays in grade but they don't know what vehicle the oil is going on. If you have a diluter, such as certain Honda's, the oil is going to thin out without question.

If I run a recommended interval of say 5 -10k, the oil will shear or be diluted to a degree and my concern is that a thin 30 will end up as a thick 20 somewhere along the way. Running a 30 that has a cSt of 10 to 11 doesn't concern me.

I suppose I could understand using the PP 5/30 if I was driving a lot on a highway but driving around town a lot, I have my doubt the PP would be ideal and end up a 20. Wouldn't I better off using a higher cSt 30? Conversely, a car calling for a x/20 that dilutes or shears would seem to benefit from running the PP.

 

[benjy]

prolly a LOT of stretching the TRUTH from oil manufacturers for sure BUT without a doubt those with newer DI only + especially those known to thin oils should as you do run a 5 or even 10W30 when its warmer + change at no more than 5 thou unless its ALL long trips, even less if ALL short trips. oil changes done at home are cheap + engines are not. owners trading often under 50 thou have few issues but like myself 200 thou on my last ride need be on top of upkeep!

 

[nlife]

I live in the North and get colder temperatures than those in the South. Thinner oils are desirable to me in the winter. On the flip side thicker oils would be more desirable in the hotter climates.

I'm currently driving a 2018 f150 3.5L EcoBoost and have no idea if it's shearing the oil. It still smells like oil not gas and the engine isn't consuming any oil, nor is the oil level increasing due to fuel dilution.

I do have PUP and PP on my shelf as the next to try since I got both at a good price. Winter is just around the corner here...

 

[Mad_Hatter]

If you have a known diluter, it's not gonna hurt to run the thickest grade allowed while under warranty. That said, if you're owners manual specs say a 5/20, 5/30 and a 10/30.. even if your 5w30 sheared or diluted to a SAE20 it would, in theory, still provide a sufficiently thick oil film...in theory. I listed those 3 grades as an example of what my OM states. I use a 5w30 in the colder fall/winter months and a 10w30 in the spring/summer. I don't have a fuel dilution issue on my port injected engine that I'm aware of (never a hint of fuel in the spent oil after 4~5k miles) but shear thinning is always a possibility, so that's why i don't bother with the 5w20. Whatever fuel economy it may provide is a fair trade off, IMO, for the thicker oil film that a Xw30 provides.

Edit: you can't look at a virgin 100c kv and say, that's too thin and will go out of grade. It may or may not. There are a lot of factors that come into play, like drain intervals and operating conditions, and some you'll never know, like the quality of the VM's. But if it makes you feel better by all means chase down the thicker 100c viscosity, it's not gonna hurt anything. I personally don't waste my time doing that for the aforementioned reasons. See Par. 1

 

[ZeeOSix]

Only way to know how a specific engine affects a specific oil in terms of shearing down and fuel dilution is to do a UOA.

 

[parshisa]

Check out UOA I've just posted. "Known" oil diluter, non oem oil grade, awesome results. Get whateverv30 weight on clearance and sleep well

 

[dblshock]

vacillate from the silly OEM specs, go much thicker 10/30, 0/40, 5/40, 10/40 predicated on low cold start temps.

 

[paoester]

Flashlightboy, fuel dilution is a problem for viscosity. When it is present in greater than about 1%, probably a good idea to go a grade thicker and let it thin down to OE spec.
Fuel lowers visc in every oil regardless of brand or type. Oil makers get their basic spec (i.e., SN, dexos1, 229.71, 508, etc.) by running tests and showing their oil's VII chemicals don't break too much. (Kurt Oban shear tests for example)
By passing those standardized shear stability tests, they can brag on marketing materials. They never claim they win against fuel dilution, only Oban-style tests.

 

[Flashlightboy]

Thanks to everyone for helping understand what I thought I surmised.

If there's demonstrable shearing or dilution through UOAs, look at the numbers and determine if the final results still offer the same in-grade performance you expected. Depending on the numbers, a high cSt within grade or a kick up in grade is not necessarily a bad thing and rather might actually be a very good thing.

 

[Mad_Hatter]

Originally Posted by Flashlightboy
Thanks to everyone for helping understand what I thought I surmised.

If there's demonstrable shearing or dilution through UOAs, look at the numbers and determine if the final results still offer the same in-grade performance you expected. Depending on the numbers, a high cSt within grade or a kick up in grade is not necessarily a bad thing and rather might actually be a very good thing.

Sounds about right.ðŸ‘

 

[Impatient]

Someday i'll get off my soapbox, but after my "somewhat bad" experience with PP and PUP 5w30, that day has not arrived. Both ended up with viscosity below 8.5 cst (PP @ 8.2 after 6k miles, PUP @ 8.4 after a mere 900 miles). Yes, fuel in the 4.3-4.7% range. Pennzoil advertised cst over 10 back then (a year ago), but voa's showed it was well below 10 to begin with. So they start out thin, and just get thinner, at least in a hostile TGDI fuel-diluting environment. So, IMHO, neither PP nor PUP is a good fit for a turbo diluter (unless your vehicle calls for 5w20, and you are using Plat 5w30 to compensate). I've seen other SOPUS oil (namely RGT, and QSUD) actually drop more (uncertain whether dilute or shear), but because they started out much higher (over 11 cst), there was more margin for thinning without ending up toooo thin. Also, someone's recent UOA's on Pennzoil Gold 0w20 (semi-conventional) had better ending visc than my 5w30, so maybe it's a Platinum or GTL thing. Also, the 2.6 TBN of my PP was pretty low after 6.1k mi.

I don't have results to back this up, but maybe a euro 0w40 would do better (if specs call for 5w30), though current off-the-shelf varieties apparently shear quite a bit. Still, you would be compensating somewhat by starting out with the 40 weight. Heck, some guys are going "up" even further with 5w40's. Parshisa's Amsoil Signature UOA mentioned above remained in grade better as well, so maybe "quality" (like Amsoil) vs "quantity" (like 40wt vs 30wt) is also a good approach. Or maybe I just have a P.O.S. engine.

Originally Posted by Flashlightboy
I read a lot and post infrequently but this is a topic that I can't quite wrap my head around and perhaps the answer is obvious and I just don't see it.

I'm going to use PP 5/30 as an example but any other oil in the same grade with a 9 range cSt would be similar, I think.

We know that that shearing and dilution decrease the viscosity and Pennzoil, like the the others, routinely say their oil is resistant to shearing and stays in grade but they don't know what vehicle the oil is going on. If you have a diluter, such as certain Honda's, the oil is going to thin out without question.

If I run a recommended interval of say 5 -10k, the oil will shear or be diluted to a degree and my concern is that a thin 30 will end up as a thick 20 somewhere along the way. Running a 30 that has a cSt of 10 to 11 doesn't concern me.

I suppose I could understand using the PP 5/30 if I was driving a lot on a highway but driving around town a lot, I have my doubt the PP would be ideal and end up a 20. Wouldn't I better off using a higher cSt 30? Conversely, a car calling for a x/20 that dilutes or shears would seem to benefit from running the PP.

 

[DirectRejection]

Oils have been known to shear, then stabilize
.TBNs have been known to drop, then hover.
If I remember correctly, PPHM can be surprisingly thin.

Maybe you'd be more comfortable with your Castrol in your EB ?

 

[jbutch]

Originally Posted by Flashlightboy
Thanks to everyone for helping understand what I thought I surmised.

If there's demonstrable shearing or dilution through UOAs, look at the numbers and determine if the final results still offer the same in-grade performance you expected. Depending on the numbers, a high cSt within grade or a kick up in grade is not necessarily a bad thing and rather might actually be a very good thing.



I had better results with Non-GF5 (HDEO/C3, ect) oils in my TGDI.

They tend to be on the thicker end of their grade and in my case they sheared a lot less.

They also resulted in lower wear metals.

If you are interested here is my latest UOA, including past ones.

 

[Mad_Hatter]

With a +4% fuel dilution I'm going to go with POS engine. With that amount of fuel in the oil, most any SAE30 is gonna have trouble staying above 9.3cSt. But since you can't really do much about the FD issue, sans limiting idling, shorter drain intervals and trying to burn it off, you're reduced to running the thickest 30 you can find or even going up to a 40 like you mentioned. I don't think brand is really that important here...cSt (and TBN to a lesser degree) probably takes precedence in the decision making process, at least to me it would. Dino v. syn doesn't really matter either but if it were me I'd shorten up the oci's and use a cheaper dino so I'm not wasting money on a full syn that I'm not going to run beyond say, 5k miles. At that oci today's dino's work just as good as any FS. Maybe a 5w/10w40 or an HDEO or dual rated lube with a high(er) TBN might be something you look into???

 

[Impatient]

Originally Posted by Direct_Rejection

... If I remember correctly, PPHM can be surprisingly thin.

Maybe you'd be more comfortable with your Castrol in your EB ?


I bet you're right. Some UOA info coming fairly soon on the Ford. Getting hard to find that Castrol, but I've started looking for it again, and/or their Euro 0w40.

 

[pitzel]

You'll get the shearing initially, but over time, viscosity thickening actually will be the problem. That's why minor fuel dilution + TGDI is a match made in heaven for *long* (if not extreme) drain intervals, with the possibility of the oil remaining in-grade for dramatically longer than engines that only suffer negligible fuel dilution. So that the oil is actually run into the regime in which it thickens, for which the minor amount of fuel dilution will cause thinning down to being an in-grade viscosity. The cleanliness of GDI combustion also enhances the ability of such oils to withstand long drain intervals. The protective effect of minimizing oil changes (and exposure to virgin oil) is also quite positive for intakes that suffer contamination by recirculated evaporation products of virgin motor oil.

Of course situations in which fuel dilution is not self-limiting have to be identified, and may render such a situation unsuitable for the long drain intervals needed to produce viscosity thickening. I'd expect a plot of viscosity vs. engine operating time to have somewhat of a shallow "V" shape -- with operators potentially freaking out at the bottom of the "V".

 

[ka9mnx]

I don't consider fuel dilution back into grade a good thing.

 

[turnbowm]

Originally Posted by pitzel
....The cleanliness of GDI combustion also enhances the ability of such oils to withstand long drain intervals....

The incomplete combustion of GDI/TGDI engines is anything but clean. Wipe your finger around the inside of the tailpipe for a real shocker

 

[Bryanccfshr]

Nope, not with abrasive soot that GDI produces.


https://www.sciencedirect.com/science/article/pii/S0301679X15000432

Originally Posted by pitzel
You'll get the shearing initially, but over time, viscosity thickening actually will be the problem. That's why minor fuel dilution + TGDI is a match made in heaven for *long* (if not extreme) drain intervals, with the possibility of the oil remaining in-grade for dramatically longer than engines that only suffer negligible fuel dilution. So that the oil is actually run into the regime in which it thickens, for which the minor amount of fuel dilution will cause thinning down to being an in-grade viscosity. The cleanliness of GDI combustion also enhances the ability of such oils to withstand long drain intervals. The protective effect of minimizing oil changes (and exposure to virgin oil) is also quite positive for intakes that suffer contamination by recirculated evaporation products of virgin motor oil.

Of course situations in which fuel dilution is not self-limiting have to be identified, and may render such a situation unsuitable for the long drain intervals needed to produce viscosity thickening. I'd expect a plot of viscosity vs. engine operating time to have somewhat of a shallow "V" shape -- with operators potentially freaking out at the bottom of the "V".

 

[wemay]

Originally Posted by turnbowm
Originally Posted by pitzel
....The cleanliness of GDI combustion also enhances the ability of such oils to withstand long drain intervals....

The incomplete combustion of GDI/TGDI engines is anything but clean. Wipe your finger around the inside of the tailpipe for a real shocker


Every GDi H/K I've owned had the excessive soot you mention. The one exception is my current Sportage. For whatever reason, it has no soot at all. The Santa Fe Sport's tailpipe, on the other hand, feels like a charcoal grill.