Assuming your car can take 10w30 and you live in a relatively pretty warm climate, would you get a better oil for less by going for the 0w40? I do know about the jugs vs. quart bottles issue when comparing these oils but lets just go with the assumption that M1 EP is more then M1 since Advance had oil change specials with them where the EP was $2 more.
M1 0w40 Stats
Viscocity: 78.30 cSt@40C 14.00 cSt@100C
VI: 186.09
HT/HS: 3.70
M1 10w30 EP Stats
Viscocity: 66.10 cSt@40C 10.70 cSt@100C
VI: 152.81
HT/HS: 3.10
While you might think that M1 0w40's 40C cSt is high, M1 HM 10w30 has a 40C viscocity of 78.20 cSt
M1 0w40 Stats
Viscocity: 78.30 cSt@40C 14.00 cSt@100C
VI: 186.09
HT/HS: 3.70
M1 10w30 EP Stats
Viscocity: 66.10 cSt@40C 10.70 cSt@100C
VI: 152.81
HT/HS: 3.10
While you might think that M1 0w40's 40C cSt is high, M1 HM 10w30 has a 40C viscocity of 78.20 cSt