GDI = Gas Direct Injection & TGDI = Turbo Gas Direct Injection engines with some age are showing Low Speed Pre-Ignition problems that can be traced to oil type & recipe problems.
Oil vapors, deposits ect in the ring land area at the piston edges can cause pre-ignition when the engine is under a heavy load, especially gdi turbo engines that are lugged at low speed. This has been reported to have been so bad in some cases as to have collapsed the ring lands.
Lubes with high calcium additive content are thought to be more at risk for LSPI. A heads up informative read on some findings here, for those with this kind of power plant.. Page 43 - Fuels & Lubes International 2013 - Quarter 3

 

This can also be called Super Knock. It seems various things are contributing to this problem and most likely that is based on engine design. Excess fuel in engine oil, low tension rings letting oil slip by into cylinder, etc. Then you have this oil igniting. On some of the newer engines they are not totally solving this problem, but are at least working to have only one knock happen, instead of numerous ones during each power stroke.

 

More LSPI input from Infineum, with some engine damage photos, Investigating low speed pre-ignition

 

More LSPI input from Chevron/Oronite. https://www.oronite.com/products/lspi.asp

 

Q: Could you address operators of GDI-Turbo vehicles regarding the effects of certain additives such as calcium and their impact on LSPI (low speed pre-ignition)? There's much discussion and concern by operators of these vehicles that Pennzoil's additive packages are predisposed to LSPI as compared to other brands.

A: Low speed pre-ignition (LSPI) is more a phenomenon of engine design – and as you mentioned, occurs more frequently in gasoline direct injection (GDI) turbocharged engines. It is really a phenomenon for prototype or experimental engines that are still in the Research & Development phase, and oils with high levels of calcium-based detergents can increase LSPI frequency. HOWEVER, by the time the engine is fully designed and released to the market, it must be compatible with the available motor oils in the marketplace. Thus said, there is no need for concern.

Posted on Bob is the Oil Guy in a question and answer session with Pennzoil engineers.

 

http://www.api.org/~/media/Files/Cer...look.pdf?la=en

More interesting data input from respected SwRI on high calcium loaded lubes showing more instances of LSPI, in slide 8.
Note that the graph shows higher LSPI events for higher calcium loaded engine oils, than magnesium loaded recipes.

SO, those with GDI, or TGDI engines, would be wise to consider using engine oils with a Lower dose of calcium in their recipes, to try & avoid the type of expensive & unpredictable LSPI event & resultant engine damage it can cause, like shown in slide 7.

The LSPI event is sorta like spark knock, in that its a pre ignition heat caused event, but its different in that it occurs in a different area of the combustion chamber & for different condition reasons.
Because of engine design & operation differences, the combustion chamber pressures on GDI=Gas Direct Injection & TGDI=Turbo Gas Direct Injection engines is much greater, so when the unpredictable LSPI event occurs, it puts Way more pressure on things than a port fuel injected spark knock engine would normally see.

So LSPI events have produced collapsed piston ring lands & other serious combustion chamber damage, as noted in other studies.

Yes TGDI engines that are lugged at low speed are more prone to LSPI, but that hasn't been the only operating condition that'll produce the problem.

At this point LSPI is not Fully understood, but some really good research by a number of well respected industry folks, have shown, like in slide 8, that high calcium loaded lubes, with calcium above 0.15%, would be wise to avoid right now.
Its our engine, so we can choose to use what ever we like, but we have to warranty our choices, so consider choosing wisely, based on the latest data inputs!!!!

The upcoming GF-6 lubes will take all of this info into consideration in their recipes, but those lubes are a year or two away, but some lube blenders recognizing the latest research findings, are already changing/lowering % calcium content. So Much lower calcium content recipes are Now available to us & we can research some of the latest VOA = Virgin Oil Analysis findings at PQIA = Petroleum Quality Institute Of America, here. The Petroleum Quality Institute of America
,A bunch more thoughts for consideration.

 

Engine design and lube requirements are a two way street and of course engine designers have to keep one eye solidly on available oil technology but lubricant manufacturers also have to provide updated lubricants that meet the evolving requirements of new engine designs. The new API CK-4 and FA-4 Diesel engine oil standards are perfect examples.

The LSPI issue is a problem to be solved by all concerned, it's not just a laboratory experimental prototype engine design issue. Those prototype engines will soon be in our cars and trucks.

If there's to be no need for concern it's because the oil and engine manufacturers will take the bull by the horns and work through the problems together.

 

More LSPI info for consideration. LSPI: A knock on the newest engines | F+L Asia -F+L Asia

 

BUMP:

More GDI & PFI engine deposit loading tests. http://www.pecj.or.jp/japanese/overs...rence12-19.pdf

 

More interesting LSPI input from Infineum. Quenching low-speed pre-ignition

 

SN+ motor oil licensing date has finally been agreed upon & will begin May-1-2018.
EDIT: The donut will look like the one in this article https://noln.net/2018/04/01/on-the-c...gf-6-and-more/

SO, those of us with GDI = Gas Direct Injection, or TGDI = Turbo Gas Direct Injection engines can find a new ILSAC SN+ logo on our oil container & be assured these lubes additive package will address the LSPI = Low Speed Pre-Ignition problems, that earlier high = greater than 2000ppm calcium(Ca) detergent &/or Sodium(Na) containing detergent SN recipe engine oils, that were found to be causing LSPI events, are now Way less likely to occur, IF we are wise & choose a low calcium, or no sodium containing engine oil detergent recipes.

We can visit PQIA = Petroleum Quality Institute Of America here PQIA PCMO Sample Summary List to scroll down the list to find & click on the name of the lube we're using, or want to use & that'll open a VOA = Virgin Oil Analysis test of the lube in question, then look for a up to date VOA of it's Ca & Na level test results. We would be wise to choose a lube with less than 2000ppm Ca & low, or no Na & lately it's been suggested a recipe with less than 1500ppm Ca & No Na detergents should be used in TGDI, or GDI engines.
For instance Valvolene which had been using Na detergent in its engine oil recipe, has reformulated to remove Na from its brand, or greatly reduce, or remove Na in other formulations it makes for its customers.
If you have a stash of oil containing high amounts of those detergents, it would be wise to use the stash in older NON TGDI, ot GDI engines in your family or business fleet.

Many lube marketers have been lowering their engine oil lube Ca & Na content over the past two years or so, such that we may find our lube choice is already meeting the new SN+ recipe. This SN+ is going to be part of the much delayed ILSAC GF-6 roll out, that's now not expected to happen until 2020. Yup GF-6 will be at least 4 years behind scheduled roll out. It was to have been in place for the new GDI & TGDI engines that began hitting the market in larger numbers earlier this decade, but the testing for these new oils wasn't in place & has taken Much longer than expected to develop. All of the GF-6 tests have about been finished, tested & approved, so maybe the 2020 roll out date for GF-6 can be met? Anyway we now have SN+ that'll address the LSPI problem & the OEM's were adamant about getting the LSPI problem addressed in the interim.

 

https://www.sciencedirect.com/scienc...16236118308858 Bottom line, those of us with GDI, or TGDI engines would be wise to be mindful of what we pour into the gas tank to mix with our fuel, lest we upset the apple cart & begin having LSPI events due to upsetting the flame front of our fuel of choice recipe & begin having LSPI events.

Lots to consider now days with the high strung finely tuned down sized engines of today.
They are efficient power plants that are fun to drive & go at throttle up, but this study seems to suggest it doesn't seem wise to be lackadaisical in the quality of fuel we feed these puppies & that would include aftermarket fuel additives we pour in.

Refer to that great unread document called Owner Manual, for its recommendations on fuels & any recommended additives & their use timing in the OCI & stick with that, as it seems that API SN+ engine lube, with its reduction of Calcium & Sodium in the engine oil recipe, isn't the total answer in preventing LSPI events, seems fuel composition is still out there too, so be careful what you feed your high strung ride & stay tuned for more LSPI best practice information, as it seems to be an ongoing learning event for all.