[mwebb]

the viscosity of the oil is not as important as the
specifications of the oil -
never use a NON synthetic oil
never use synthetic oil or alleged synthetic oil that does not have
an ACEA specification , the API and ILSAC specifications are poor substitutes

an ACEA A1 B1 - A5 B5 in 5w30 , similar to the GM DEXOS1 oil would be slightly better for fuel economy at the expense of lesser values of resistance to shear and deposit control GM dexos information center Mobil one 5w30 is a DEXOS1 approved oil and ACEA A1 B1 - A5 B5

not as good a choice as ...

an
ACEA A3 B3 - A3 B4 in 5w30 or 0w30 like the GC castrol "european" oil would be a better choice for resistance to shear and deposit control at the expense of fuel economy -

FE differences between ACEA A1 B1 - A5 B5 and ACEA A3 B3 - A3 B4 are measured in very small values .

because the oil change interval minimum on either of the above oils would be 6000 miles , even though they cost more than the much lesser quality oils , that are replaced at 3ooo miler intervals , the better oils listed above are cheaper to use - and either is infinitely a better oil

study and learn at the bitog forums
in any event
do not use 0w20 oil in your engine .
pain is a good teacher , always ready to provide another lesson .
school is always open