Just out of morbid curiosity, what is it about an SF oil that's (allegedly) likely to kill a post-88 car ... and what failure mode would be expected?
Originally Posted By: circuitsmith
Newer designs have hotter hot spots the oil encounters as it circulates through the engine.
OK, that makes sense. Thanks for the reply.
Originally Posted By: circuitsmith
Narrower rod & main bearings,
Can't see that. If bearings are getting hot enough to break down ANY oil then they're broken.
Originally Posted By: circuitsmith
tighter ring packs nearer the top of the piston (reduces the crevice between the piston and cylinder, which reduces HC emissions),
OK, that makes sense.
Originally Posted By: circuitsmith
also there's more HP per displacement, which makes more heat and stress.
Not sure I see that either. It describes a generalised input of heat into the system, rather than a hot spot. Provided the cooling system is adequate, generalised heat input shouldn't lead to higher general temperatures, so shouldn't break down oil. If it makes the hot-spots hotter, that'd do it.
Originally Posted By: circuitsmith
There's also more complex valvetrains to protect.
Daresay, but I don't see why a complex system is harder to lubricate than a simple one, though it may have more failure points.
I suppose hydraulic tappets and chain tensioners are a specific oil-vulnerability but I think they existed pre-1988, though probably got commoner after.
I wonder if the increase in [censored] plastic chain guides has anything to do with it, but I think they existed pre-1988 too.