Mobil 1 Extended Performance 5w30 or 10w30

[surfstar]

I usually buy Mobil 1 10w30 in the 5 qt jugs at Walmart for $20. Since I got some Pep Boys buy 3 get 3 free coupons, I would like to mix in some Mobil 1 Extended Performance for my oil changes. My sump is 3.5 qts, so I will probably go w/ 1.5 EP and 2 of Mobil 1. My question is should I go for the EP 5 or 10w30? I use Mobil 1 10w30 and am happy with it, but the EP versions seem to get thicker during an OCI. That would lead me towards the 5w, but the HTHS is nice on the 10w, and I live in CA, with no real winter to speak of. Here's the specs:

Mobil 1 Extended Performance
5w30
10W-30

SAE Grade 5w30 10w30
Viscosity, ASTM D 445
cSt @ 40º C 57.3 66.57
cSt @ 100º C 10.25 10.5
Viscosity Index, ASTM D 2270 169 146
Sulfated Ash, wt%, ASTM D 874 1.35 1.38
HTHS Viscosity, mPa·s @ 150ºC ASTM D 4683
3.08 3.21
Pour Point, ºC, ASTM D 97 -45 -54
Flash Point, ºC, ASTM D 92 226 224
Density @15º C kg/l, ASTM D 4052 0.861 0.871
Mobil's page

 

[MrClutch]

I also live in CA, in Los Angeles to be specific. It gets hot here so there is no need for 5w30, so go ahead and use 10w30. And 10w30 i heard does not use VI improvers and it is more shear stable. And wheather to use EP or regular is a matter of choice, it looks like the EP has more cleaning ability over the regular M1. And no, these oils should not thicken up.

 

[Ray H]

Is it true the Mobil 1 Extended Performance flavors are still rated "SL"?

 

[surfstar]

EP 5w30 and 10w30 are:

API SL,SJ,SH/CF
ACEA A1,B1,A5,B5

10w40 and 15w50 are:
API SM,SL,SJ,SH/CF
ACEA A3,B3,B4