What's the Secret in the Additive Pkg that Reduces Chance of LSPI Events ?

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LoneRanger

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So SN+ and 1Dexos Gen 2 spec are aimed directly at combating Low Speed Premature Ignition (LSPI) in gasoline direct injection turbocharged motors. Poking around in the VOA's on the PQI website seems to show boron in significant amounts in some of the Dexos and SN Plus synthetics. Is boron the magic bullet?
 
Follow-up question: Additive package aside, would either PAO or Ester as base oils be less prone to igniting that Group III?
 
Sodium: eliminated
Calcium: reduced to below ~2000 ppm
Magnesium: increased
Molybdenum: added

Yes, that link has been discussed before. If I find it, I'll share.
 
Originally Posted by wemay
Sodium: eliminated
Calcium: reduced to below ~2000 ppm
Magnesium: increased
Molybdenum: added
Yes, that link has been discussed before. If I find it, I'll share.

Great summary by wemay...at least one study I saw a while ago reported that ZDDP was a powerful mitigator of LSPI, but levels of this cannot be increased randomly for SN/GF5 oils.
I suspect that this is why the use of "euro" A3/B4 oils does not seem to result in higher occurrence of LSPI, as they tend to be high in ZDDP...just a guess on my part.

I did also note with great interest that the authors of another LSPI study modified the injector in the cylinder they were focusing on to spray more fuel on the cylinder wall than normal in an attempt to cause more LSPI events...this may be a hint as to why some DIT engine designs seem to have more trouble with LSPI than others.
 
Opps. We designed the fueling system wrong, increased the compression too high, geared the vehicle too tall, recommend Regular 87octane fuel - pendulum moved to far to ECONOMY.

Let's blame the ..... uhhh ..... OIL!

Come ON! what do you expect would happen? REALLY!

Oh, but there is a study that shows ....Ca Carbamate and blah blah.

Sorry. I'm not biting.
 
Originally Posted by Skippy722
I found this, according to them group IV has the highest likelihood of causing it.

https://www.infineuminsight.com/articles/passenger-cars/lspi-and-lubricant-auto-ignition/


So, with the exception of Group V, a group II-III semi syn (conventional SN+) is actually better than Group III which is actually better than Group IV? Or maybe those Mobil group II basestocks which meet SN+ with no group III is actually a good thing
 
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Originally Posted by csandste
LSPI is almost always restricted to Turbo AND GDI or are there cases of turbo alone or GDI alone?



Turbo alone = That's an entire degree in itself - spanning the last 60-70 years.
Detonation can and does occur for all kinds of reasons.
NO ONE "singles out" LSPI by itself.

GDI Alone = Cylinder pressures aren't high enough,
or ECU management can handle the events just fine by modifying fuel and speak timing as needed.
 
Originally Posted by LoneRanger
Originally Posted by Skippy722
I found this, according to them group IV has the highest likelihood of causing it.
https://www.infineuminsight.com/articles/passenger-cars/lspi-and-lubricant-auto-ignition/

Excellent article. As far as base oil, looks like Grp V is best mitigator of LSPI. A group five oil with an additive pkg formulated to help mitigate LSPI looks like the way to go.

I'm not really sure what to make of that paper....they never seem to establish a correlation between actual LSPI and their Ignition Quality Test (IQT) results.
These lines at the end of the summary are very interesting...
"However, many questions remain unanswered, in particular why calcium has an LSPI-promoting effect while magnesium does not. Perhaps further modification of the IQT to allow solid-phase auto-ignition (auto-ignition catalysed by a solid deposit) may help to answer this question."
I have also read elsewhere that there is a strong suspicion that some kind of hot solid being scraped off the wall by the motion of the cylinder is the physical trigger for an LSPI event, and this might explain why the presence of calcium in the fuel/oil mixture used in the IQT tests had no effect upon their results even though it is very well established that it affects LSPI frequency.
 
GDI engines have a very short time (compression stroke) to atomize the fuel. Add hot, and more, air from a turbo and the problem is compounded (lean). Non-turbo engines don't seem to have the problem. And, yes, injectors spraying fuel onto the cylinder walls doesn't help since the fuel gets trapped between the top piston ring and the top of the piston.

I think Boron also helped reduce LSPI?
 
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I'm using group III now, running my Soul to a mileage number divisible by 5000 (59000 to 65000). The reference to Group II being better than III-!V for LSPI, reinforces my notion to go back to a conventional (actually 50-50 Group II-III) oil-- VWB or QS Conventional (which was late to the SN+ party but bottles now show it), and change at 5K intervals. That did well on my Kia Rio and other HyunKia's owned as well. If I was able to change my own oil I'd be buying a cheap group III, I real there are other advantages that offset the increased tendencies to LSPI, which apparently isn't a problem with my GDI, non-turbo anyway.
 
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Amsoil came out and said 100% LSPI protection with their Signature Series after they lowered the Calcium so it appears that a Group IV oil with the right additive package can work just fine.
 
Originally Posted by ka9mnx
GDI engines have a very short time (compression stroke) to atomize the fuel. Add hot, and more, air from a turbo and the problem is compounded (lean). Non-turbo engines don't seem to have the problem. And, yes, injectors spraying fuel onto the cylinder walls doesn't help since the fuel gets trapped between the top piston ring and the top of the piston.

I think Boron also helped reduce LSPI?


Injector patterns may explain why HyunKia and other manufacturers request Top Tier gas and/or Techron. Keep that gas spraying in the middle.
 
Originally Posted by ARCOgraphite
Opps. We designed the fueling system wrong, increased the compression too high, geared the vehicle too tall, recommend Regular 87octane fuel - pendulum moved to far to ECONOMY.

Let's blame the ..... uhhh ..... OIL!

Come ON! what do you expect would happen? REALLY!

Oh, but there is a study that shows ....Ca Carbamate and blah blah.

Sorry. I'm not biting.


Oil isn't being blamed. Oil reformulation is an avenue we're going down because we've found that adjustments made to oil can decrease incidences of LSPI. DGI and TDGI aren't going away. So how do we make them better? Oil is one of the answers.
 
Originally Posted by StevieC
Amsoil came out and said 100% LSPI protection with their Signature Series after they lowered the Calcium so it appears that a Group IV oil with the right additive package can work just fine.


That to me sounds very unwise of Amsoil to publish such a statement.

Seems if one is running that particular Amsoil formulation and their engine is damaged from an LSPI event that's shown to be the cause, then Amsoil gets to buy the customer a new engine. Be interesting to read the fine print on a bottle of that Amsoil formulation.
 
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