R said:
try changing oil outside in January
try cranking on a sub-zero degree day
the synthetics flow just as they do in summer
but the naturals "flow" like cold maple syrup
There's nothing "natural" about any modern motor oil. They
all use polymeric VI improvers, pour point depressants,
detergents, dispersants, and any number of man-made chemicals.
In many ways, the terms "synthetic" and "conventional" are
marketing terms. Mobil checmists originally wanted to call
their product a "synthesized hydrocarbon", and sold their
first Mobil 1 offering as "Mobil SHC".
Even in cold temperatures, a 20W-50 "synthetic" oil will
flow out of the bottle slower than a "conventional" 5W-20.
The advantage of many synthetic oils is that they don't
contain waxes that tend to thicken in cold temps. Oil
processing has removed a lot of conventional oils and
pour point depressants help resist wax crystallization.
Nothing holds a constant viscosity vs temperature, but
synthetics come pretty darned close over normal North
American temps.
Depends on the "synthetic" oil. Many "synthetic" oils
these days are primarily group III base oil. Some companies
market products based on group III as "conventional". They
certain do outperform oils made even a few years ago.
Many conventional oils have quite acceptable cold weather
performance.
Now - I'm not knocking synthetic oil. I live in a temperate
climate but use Mobil 1 5W-30. It certainly is a good choice
to withstand the stresses from a turbocharged engine.