Oil Viscosity

[dr. d]

growing up in the PUV business.

both mechanics namin before strongly believes that you should use thicker oil on older engines...

it felt really strange when I read about GM's solution to their engine problems...

kasi,
heavier oils tend to result in higher engine oil pressures, to compensate for the looser tolerances "inherent in worn engines".
whether this helps stave off engine failure or not, i do not know. whether it tends to "tighten spaces between loose metal surfaces", i do not know.
but i do know that using heavier oil can tend to "silence" oil pressure gauge warnings... something bayan sellers take advantage of.

some years back,
i read that modern engines have smaller oil passages and tighter tolerances than older engines.
thus, the need for lighter oils, so that they can more easily pass thru these smaller-caliber oil passageways.