Is "synthetic blend" a legal term to use a cheaper oil?

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3,402
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Considering some other comments here, what oils are "full synthetic" and have there ever been any that are 100% synthetic?
Depends on who's definition of synthetic you use:

Castrol or Mobil.

Castrol calls their Group III basestock oils as synthetic which Mobil disagrees as they feel Group IV PAO is synthetic.

As there been any others that are fully 100% synthetic? Amsoil likes to claim this, before they diluted the lineup with the OE series oils. There's redline oils, until they started with their Professional Series oil. And of course, Mobil, until after they lose their case with Castrol, and started to dilute their PAO basestocks with Group III base stocks, iirc, starting around the "Tri-Synthetic" version of Mobil 1
 
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4,583
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Decatur AL USA
Depends on who's definition of synthetic you use:

Castrol or Mobil.

Castrol calls their Group III basestock oils as synthetic which Mobil disagrees as they feel Group IV PAO is synthetic.

As there been any others that are fully 100% synthetic? Amsoil likes to claim this, before they diluted the lineup with the OE series oils. There's redline oils, until they started with their Professional Series oil. And of course, Mobil, until after they lose their case with Castrol, and started to dilute their PAO basestocks with Group III base stocks, iirc, starting around the "Tri-Synthetic" version of Mobil 1

You mean old Mobil Definition. As far as I know Mobil Super Synthetic / Full Synthetic doesn't have any GIV or GV Base.
 

BrianApp

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MI
The only thing the manual calls for in regards to engine oil is that it have the DEXOS logo and meets that spec. No mention of conventional, synthetic, blend, or mineral, just dexos. I don't know what dexos means, I would guess a GM spec, but that is all they care about.
The question I am left with if all the car maker cares about is meeting the dexos spec then why not just use the cheapest one, which the dealer probably does. If my cheap $20 oil change meets the spec then why would anyone ever opt for a more expensive oil. Does the dealer then just stock only the cheapest dexos oil they can find for all of their work? It is hard to believe that ALL dexos certified oils will have the exact same quality and performance in the engine but the car maker doesn't care.

I always thought the term "blend" was used when they diluted the good stuff, pure synthetic, with cheap stuff but I guess dexos is dexos no matter how it is mixed.
 

BrianApp

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MI
Well I just assumed the dealer would use it. If it is actually a high grade satandard I guess I should ask and make sure they are using it on my $20 special.
 
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16,546
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Upper Midwest
The only thing the manual calls for in regards to engine oil is that it have the DEXOS logo and meets that spec. No mention of conventional, synthetic, blend, or mineral, just dexos. I don't know what dexos means, I would guess a GM spec, but that is all they care about.
The question I am left with if all the car maker cares about is meeting the dexos spec then why not just use the cheapest one, which the dealer probably does. If my cheap $20 oil change meets the spec then why would anyone ever opt for a more expensive oil. Does the dealer then just stock only the cheapest dexos oil they can find for all of their work? It is hard to believe that ALL dexos certified oils will have the exact same quality and performance in the engine but the car maker doesn't care.

I always thought the term "blend" was used when they diluted the good stuff, pure synthetic, with cheap stuff but I guess dexos is dexos no matter how it is mixed.
A dexos licensed oil is indeed what GM cares about. This is a good illustration of the fallacy of trying to read the tea leaves.
 
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15,674
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I believe Magnatec syn blend gave better results than their full syn. I remember when it was giving stellar results in Ecoboost engines. I don't think it's produced any longer, too bad.
Me too. I bought and tried when it first appeared. Fantastic stuff ( disregarding sub freezing cold starts)Then it got "watered down"
 
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15,674
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N.H, U.S.A.
I know Subaru "requiring" Synthetic oil changes have wiggle room in the O.M.
Hidden somewhere - purposefully, so dealers can up-sell their "Subaru Genuine Synthetic Oil" -
is the statement that the use of Conventional oils will provide adequate service
with no harm to the engine.

sub_conventional oil2011.JPG


And this is what M1 AFE 0W20 "Synthetic" looked like with only 5K late summer interval:

mobil10w20_5kmi-subFB_100211.JPG
 

4WD

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15,818
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Texas
I believe Magnatec syn blend gave better results than their full syn. I remember when it was giving stellar results in Ecoboost engines. I don't think it's produced any longer, too bad.
Oxidation galore in 3k is what I got from it … coal black and thixotropic in an easy engine
 
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15,674
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N.H, U.S.A.
Oxidation galore in 3k is what I got from it … coal black and thixotropic in an easy engine
Sing it: "One bad apple don't spoil the whole bunch, girl ! "

There are better oils out there agreed. But Magnatec Semi had a special "velvety" quality, like the old Red bottle QS DEFY when it first came out, or
the pre -synthetic bronze bottle Pennzoil High Mileage.

curios was then engine under 7K miles when you ran the Magnatec? and, What engine?

I vaguely recall your story, but forget the specifics.
 

4WD

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15,818
Location
Texas
Sing it: "One bad apple don't spoil the whole bunch, girl ! "

There are better oils out there agreed. But Magnatec Semi had a special "velvety" quality, like the old Red bottle QS DEFY when it first came out, or
the pre -synthetic bronze bottle Pennzoil High Mileage.

curios was then engine under 7K miles when you ran the Magnatec? and, What engine?

I vaguely recall your story, but forget the specifics.
2013 Charger with 3.6L … it did lots of short trips and still does. Had the dealer check the engine out. Good.
Have run PG, M1, QSUD, and STP in that motor on 4K changes … No issues … been a good car to date …
 

CKN

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6,100
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Utah
A dexos licensed oil is indeed what GM cares about. This is a good illustration of the fallacy of trying to read the tea leaves.

I would use any oil that has the Dexos specs. The "Cheap" oils are CostCo's Kirkland and Walmart's "SuperTech". To my knowledge those are the cheapest oils that meet Dexos specs. This is assuming no rebate games on anything else.
 
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438
Location
VA
So would a “blend” with a viscosity index of 167 be an indication that the blend has a high amount at least a groupIII base oil?
 
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128
Location
North Carolina
I know Subaru "requiring" Synthetic oil changes have wiggle room in the O.M.
Hidden somewhere - purposefully, so dealers can up-sell their "Subaru Genuine Synthetic Oil" -
is the statement that the use of Conventional oils will provide adequate service
with no harm to the engine.



My wife's Pathfinder states 0w20 Synthetic or conventional 5w30. And yes the 1 time I had a shop change it there was an argument 🤣.
 
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13,518
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Kendall, FL
@BrianApp

OP, here's some good reading on the differences in base stocks...

 
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