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Best 10w40 motor oil

T tallpaulMember
I have researched the Valvoline Durablend MSDS sheets and found the 10w40 appears to be mostly Group II base oil along with the (Valvoline Techs tell me) 30 percent synthetic, which according to the MSDS must be Group III. This would make Durablend 10w40 a pretty good dino oil. Even better that the Durablend 15w40 as its MSDS indicates about 55 percent solvent dewax base oil or in other words apparently Group I mixed with the 30 percent Group III. Both meet ACEA A3 spec, but given the better base oil (apparently from the MSDSs) I am going to go with the 10w40. Also the 10w40 is easier to get and so can be found on sale (Pep Boys $1.99 first half of August with coupon). The MSDSs are at http://msds.ashland.com/
Just change the search for criteria to "contains" and enter Durablend.

Note the 5w20 and 5w30 Durablend both have high proportions of the Group II/III base,but the 10w30 and 20w50 (like the 15w40) are more heavily weighted to the Group I base oils. Appears the tighter spreads get the cheaper base oil here.
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T tallpaulMember
It is interesting that, at least with the Durablend, they seem to put the better base oil in the wider spreads to apparently acheive uniformity of performance across the board.

With Valvoline Maxlife, though, the base oil is the same across the board, 5w30 through 20w50.

What I found very interesting was the Valvoline Synpower. The MSDSs show most of it is Group III, but the 20w50 MSDS shows Group IV.
T timerMember
I am lost !

The topic is best 10w-40 but every type but 10w-40 is discussed .

Is this topic about which 10w-40 will give the best service for the least cost or 10w-40 at any cost to include synthetic .

Also is the topic about oils only available in the USA and the vehicle type would be of some importance . 1.3 liter Mazdas would loose much power with such a thick oil but the thick oil might be needed on the planet named Mercury .
T tallpaulMember
quote:
Originally posted by Timer:
I am lost !

The topic is best 10w-40 but every type but 10w-40 is discussed .

Is this topic about which 10w-40 will give the best service for the least cost or 10w-40 at any cost to include synthetic .

Also is the topic about oils only available in the USA and the vehicle type would be of some importance . 1.3 liter Mazdas would loose much power with such a thick oil but the thick oil might be needed on the planet named Mercury .


You can make the topic go any way you'd like. So far somewhat interesting. Hey, maybe on Mercury I would need 20w50 or thicker (could add some STP maybe).

I do think 10w30 (oops, off topic) is the best compromise and starting point. That is what I run in two vehicles, but the pickup truck seems to be better on 10w40, which gives it nicer oil pressure (42 hot at 2000 rpm). Runs great. Ford has now back recommend it to 5w20--not! This one does not want the thin stuff, but maybe OK for a Focus.
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