Cold weather and the Yaris

[tmontague]

Originally Posted by IllusionX

Viscosity should be the same (within spec) mineral or synthetic.

True, like you said "within spec". I you're in an area that drops temps below what the "5w" is rated in synthetic tends to flow better at those out of range temps. That's essentially one of the sole purposes in running synthetic (grade IV not V). There is no doubt it has made the cold starts easier and smoother for me.

That being said, I have never heard a grinding noise in any car at any low temps regardles of oil. I would think it's something other than a shearing noise. Unless a gallery port is plugged an oil isn't getting there at all?