The blanket statement that high SAPS engine oils result in worse Inlet Valve Deposits on GDI engines is total and utter bollocks!!!! It may have been 11 years ago but even so, Mike McMabe should hang his head in shame for peddling such misleading and self-serving propaganda.
Okay, let's go back to 2006 when this presentation was issued. If you look at the maximum permitted Sulphated Ash levels for 'normal' ACEA oils, they appear very high ranging from 1.3% (for A1/B1) to 1.6% (for A3/B4). But these are MAXIMUM levels. There were no minimum ash levels and at the time nor were there any minimum TBN limits. The reality was that in 2006, the ash levels of these oils was no where near the maximum limits. At a rough guess, a typical European SL/CF/A3/B4/MB229.1/VW505 oil (that was sort of the typical market spec level) would have a TBN of 8-ish and an ash of 0.8-ish. In other words, ash-wise, these oils weren't a million miles from the ash specs of ACEA C2 & C3 low SAPS oils. Also, while Phosphorus wasn't explicitly limited for ACEA oils, most commercial oils had P levels of under 1000 ppm; so again, not a million miles from the 900 ppm max of most of the low SAPs grades.
Now let's look at A1/B1. A1/B1 was always something of a grudging nod by ACEA to what was happening in the US on fuel economy oils. Most of the big European OEMs didn't want it as they were still very much wedded to their 3.5 min HTHS limit, but people like Ford could see a place for 2.9 min HTHS oils in Europe. A1/B1 was US-like in other ways. It allowed oils with upto 15% Noack (vs 13% max for all other oils) so importantly it could be made from Group I/II oils. Secondly, unlike other ACEA oils, A1/B1 did not have to stay-in-grade on the KO30 shear test, meaning that it could use US-like high SSI VIIs. Thirdly, and critically, A1/B1 oils were allowed an easy ride on the Peugeot TU5 test.
There's one other relevant piece of the jigsaw to share. Whilst A1/B1 oils are notionally dual-use oils (ie for both gasoline & Diesel engines), the OEMs that plugged them did NOT recommend them for Diesel.
So now we get to this field trial that so convincingly 'demonstrated' that a Euro 3, OEM recommended, high SAPs oil gave far worse IVDs on a GDI engine than a Euro 4 low SAPs oil.
Now the presentation gives no details on what oils were compared but one might imagine a scenario where an AddCo, keen to capitalise on a new market opportunity, compares a high SAPs oil with a low SAPs oil. Obviously they want the trial to give the 'right' result that suits their commercial purposes. So what do they do? Might they compare an mineral-based, 5W30, nominally (but not really) high SAPs, A1/B1 oil (with its attendant high Noack) to a full synthetic (possibly PAO) low SAPs oil (with presumably a very low Noack). Given the mechanism by which valve deposits are formed, which do you think will demonstrate the better performance??? Well of course the low SAPs oil will so QED, high SAPs oil is bad m'kay?
Finally let's consider what Direct Gasoline Injection might have been used for this field trial. As I recall, there weren't that many around back then but one was about to be launched; the infamous Audi 2.0L TFSI engine. Yep. That one. The one that ate oil like it was going out of style. The one that suffered from obscene amounts of inlet valve deposits. The one that was subject to a class action lawsuit suit in the US. Do we still think it's right to blame high SAPs oil for causing IVD problems or might it possibly be that the engine itself was a dog??
Some folks really do need to stop treating every single thing they read on the internet as Gospel and mindlessly parroting messages that are simply not true.
