In article , mike wrote:
On 25-03-2021 23:12 Scott Dorsey wrote:

Not relevant, because "blended" doesn't mean what it seems to. In fact,
"synthetic" doesn't even mean what it seems to.

The vast majority of "synthetic" oils sold in the US are not legal to sell
as synthetic in Europe.

Hint: "synthetic" does not necessarily mean the base oil has been synthesized
from monomers. Even in Europe.

What always matters to me is HOW to make a rational intelligent comparison.

Aside from a few obvious and measurable things like ZDDP levels, and a few
other things to do with the additive package you really can't.

With a newer car you can make sure that the oil meets or exceeds the
manufacturer's specification for the vehicle, and that's really all you can
do.

With an older car, the manufacturer's specification may no longer even be
relevant. In that case, all you can do is guess, unless you want to do
an oil analysis with every change.

Does anyone have a good reference for what important specs to look for on
the jug of each container of synthetic (blended or otherwise) motor oil?

Or is all we've got the known General Motors, API and SAE certifications?

That's all you'll find on the jug. You may be able to get a more detailed
datasheet, but for instance knowing that a high ZDDP level is important for
engines with flat tappets but not for engines with roller lifters is about
as far as you can go with the information on the datasheet.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."