Specs are fine for being assured minimum requirements in a handful of parameters, it's too bad real-life parameters are infinite and uncontrolled. Plenty of products (in general) pass QA and durability testing only to fail IRL.
The Euros, Germans in particular have always demanded certain specs and high viscosity (even if it's fake VII viscosity
), but let's be honest, their engines leave a lot to be desired in terms of oiling systems. Arguably, they get the most synthetic 0Ws around (because specs demand it), yet many of the engines are quite prone to sludge and varnish. Some even need 10W60 to stay together... [censored]? Compared to a Japanese engine running GrIII and II 20 blends, why don't they suffer such consistent varnishing and wiped cams (VW) or bearings (BMW) etc? (can't help but think how much differently, straighter the oils are formulated.....) It's a paradox!!
Or is it?
Compare the base viscosities used. Compare the reliance on VIIs.
If you take the driest base fluids like PAO, which absolutely rejects contaminant solubility/dispersency, choose the lowest viscosity of such and then load it up with plastic (acrylates) and rubber (OCP) VIIs that are less stable than the base oil to meet viscosity, and what will you expect? The oxidation stability of the PAO is mitigated by using a) the lowest viscosity of such (4cSt) AND b) the load of VIIs. Not even to mention relatively poor NOACK vs the other grades. The dispersant gets NO help from the base oil to keep junk in solution, so where is the next likely place for the junk to go than onto the internal surfaces of the engine? But wait, it gets better! Once a layer of polar junk varnish is established on the metal surfaces, those surfaces actively PULL more junk out of the oil which naturally wants to reject it and the varnish layer builds up even faster! No wonder so much varnish winds up on the metal surfaces instead. Then there's the temporary and permanent shearing. VII laden, wide-spread grades also feature oil films that break down more rapidly at high temperatures NOT tested for.
If UOAs are any indication, the HTHS and fake viscosity doesn't even yeild better ring wear vs a less VII laden oil. Why should that surprise anyone? What are the VIIs doing in the ring pack? Breaking down to the base oil viscosity that's what! (what does a 4-5cSt base@a lowly 100C look like at 250+C? What does 3.5cP of VII HTHSV look like at 250+C? No one seems to care about viscosity behaviors past CCS, 40C, 100C and 150C...
b-b-but that's a stereotype, not every German engine is varnished
And congratulations to all who have clean German engines, but what does it mean? That less VII-reliant oil won't do any better in any other part of the engine?
By time you're seeing varnish under your valve cover, better believe the filth is well established on your rings. Even if engines can run rather acceptably with varnished rings (like MOST engines do), that's not something I want to allow because things can go south fast, like oil burning and compromized ring sealing. I'm not an apologist for oil burning like many on here are.... I find it absolutely unacceptable and will do nothing to further enable it, and everything to mitigate it.
There is no HTHSV test higher than 150C that I'm aware of, but there are local areas in an engine that handily exceed 150C. No one likes ring deposits, and virtually every engine has them. Why would I want to put enormous plastic (or rubber) tumbleweed molecules in that environment, regardless of base oil? And especially when I'll never take advantage of the 0W rating it was built for..... the WHY begs for justification.... a reason that is more comprehensive than "but printed materials tell me so".
That's fine if that's what you're about but it's about optimization for me, not idiot-proofing. It's not about getting more miles out of the engine, it's about getting more QUALITY miles out of it ie. best compression, cleanest ring packs for as deep into the service life as possible... nuances of machinery maintenance
'Good enough', 'fine' and 'acceptable' aren't goals of mine. If I don't need the cold cranking, I don't need the base 4, the rubber or the plastic in my oil. Simple as that. This is the path my oil journey has taken me to
