Technical reasons for blend vs. straight synth

[Peva]

I can imagine someone arguing that they might use a blend instead of 100% synthetic oil to "save money" on the oil at each change.

But are there technical (synergistic) benefits of a blend (say 1 qt. dino to 4 qts. synth) over stright dino or straight synth?

I asked this in a different way here: http://theoildrop.server101.com/forums/s...ge=0#Post859493, but anyone addressing it was dependent on them remembering such an article from 30 years ago (which apparently no one did)

, when really I want to know of the validity (if it exists) of a technical argument for using a blend.

TIA.

 

[Al]

First of all: "True" synthetic oils are German Castrol, Amsoil, RedLine, Royal Purple, Motul. The rest of common "Synthetic Oils" are not true synthetics. They are Group III oils. Some oils that are not marked "Blends" are really a blend of Group III and conventional oil. They are Conoco Phillips oils and Motorcraft oils. There may be others.

I'm not sure I would pay the higher price for a "Blend" when you can get Conoco/Motorcraft oils at not much of a premium. Very little advantage (to me) of a GroupIII blend.

 

[TallPaul]

Maxlife blend has PAO and is very good.

 

[Peva]

OK - Thanks for the good feedback that allows me to refine my question and now actually breaks it into 2 questions:
(1) Are there technical (synergistic) benefits in a blend of true synthtiec oil and conventional oil (say 4-to-1 or 3-to-2). IOW, is there any characteristic of a true synthetic oil that is subpar (relative to conventional oil) that can be improved by adding some amount of conventional oil without seriously compromising the good properties of the true synthetic.
(2) Are there technical (synergistic) benefits in a blend of Group III oil and conventional oil (say 4-to-1 or 3-to-2). IOW, is there any characteristic of a Group III oil that is subpar (relative to conventional oil) that can be improved by adding some amount of conventional oil without seriously compromising the good properties of the Group III oil.

 

[JAG]

1. A very well formulated synthetic will only be weakened by adding a very well formulated conventional oil...assuming they are designed for similar applications. A so-so synthetic could concievably be improved (in some ways but not all) by a very well formulated conventional oil.
2. The only main things Group 2 has over Group 3 is solubility (of additives and some contaminants) and seal swell properties. If that's accounted for by other ingredients, having more Group 2 in a 2/3 blend will just make it worse.

In practice, it's hard to apply these rules because we don't know enough about the formulations or their strengths and weaknesses.

 

[JAG]

I should have said that usually a blend by Brand X will be better than conventional oil by Brand X. They improve the formulation by taking all factors into account. I was thinking your question was more about you blending different oils.

 

[Blue99]

Off the top of my head, I can’t even think of a “syn blend” that is even a 50-50 mix, in almost all cases, it’s a conventional base oil with a 40% or less percentage of synthetic mixed in to help out with volatility & the low temp spec’s.

Synthetic base oils typically are blended with an additive for seal swell & soluability, but this fluid is not generally considered to be part of the base oil blend.

As the VI index of a synthetic base oil increases, the heat & oxidation resistant properties will also increase. This resistance is aided by the straight chain paraffinic nature of the synthetic molecular structure.

Blending in a typical Grp I or Grp II branched chain hydrocarbon base oil will decrease the synthetic base oil’s ability to resist heat, fuel and moisture.

 

[PT1]

Quote:

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Maxlife blend has PAO and is very good.

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Maxlife and PP are no doubt the best values in the marketplace for probably 95% of the people on this forum.

OK start the flamer

 

[KieferS]

i heard maxlife can damage seals if you use it for a while and switch to something else because it swells the seals, and they go back to their normal size again once you stop using it. Wasn't that a Valvoline guy that said that?