Engine oil. Why the wildly opposing opinions?

[chuck hahn]

Plain ole Valvoline 10W40 in mine..never had an oil related problem so far.

[bbjumper]

All you need to know about oil

Best information I have found concerning oil and the GS..

Cheers

http://www.widman.biz/uploads/Corvair_oil.pdf

[7981GS]

Excellent write up with clear information!
Thanks for sharing that link!

From that study:

Base oil:
There are several different base oils available to formulate motor oils. The base oils used in the 1960’s are what we call today API Group I, although some fall in the high aromatic sub- classification and some in the low aromatic sub-classification (This difference is important when we discuss additives). Today Group I oils (considered mineral oils, or “dino” oils) continue to be marketed, but in the US it is more common to find API Group II (still considered to be mineral oils), some API Group II+, more API Group III (considered “synthetic” after Mobil lost an argument against Castrol), and mixtures of API Group IV and V (traditional synthetics). The original synthetics were pure Group IV base stocks, and due to lack of solvency did not mix well with the residuals of Group I and Group II oils and shrunk oil seals, creating the concept (Myth) that you cannot change to synthetics after using mineral oils.
• Group I oils are solvent refined and normally low in natural viscosity index, although some oil fields produce better grades than others. They have 20 to 30% aromatics, high nitrogen and sulfur.
• Group II oils are hydroprocessed oils (or solvent refined and then hydrotreated). Normally 92% to 99% of the molecules are saturated in the bombardment of hydrogen, creating a clean, stable base oil and eliminating almost all aromatics, sulfur, and nitrogen.
• Group II+ oils are hydroprocessed to a quality somewhere between Group II and Group III.
• Group III oils are severely hydroprocessed, creating base oils that under some conditions give equal performance to traditional synthetic oils.
• Group IV oils are PAO (Polyalphaolefin) synthetics. These are excellent lubricants but have very low solvency when used by themselves, not mixing well with other oils, additives or contaminants, and causing hardening of seals and gaskets. Fully formulated PAO based oils use esters or other ingredients to increase their solvency.
• Group V oils are everything else synthetic. In general the esters and diesters of various formulations are used to mix in small percentages with PAO oils to give then the necessary solvency and help them maintain a clean engine, softening the seals to avoid leakage. The category also includes other types of oils used for specialty products or to thicken group I, II, III or IV oils.

Evaporation:
All oils are tested for evaporation for 1 hour in an oven at 250° C in a test called NOAK. An SJ oil is allowed to have 20% evaporation. An SL oil is allowed only 15%, and an CI-4 oil is only allowed 13%. Many synthetic oils are around 5% to 8%. The higher the number, the thicker the oil gets in service and the more you will have to add.

Friction Modifiers:
Every oil is designed for a specific purpose. In general, motor oils are designed to be as slick as possible and to reduce friction as much as possible. These are generally esters (group V synthetic) and fatty acids whose molecules also attach to the metallic surfaces to reduce friction during sliding action. If the contact is heavy they are pulled off, allowing friction and wear unless there are enough anti-wear additives to take over.


Daniel

[850 Combat]

Even synthetics have to come from oil wells or gas wells. The term "Dyno" makes no sense as either or description. I believe that polyalphaolefin oils use ethylene gas a feed stock, which I believe comes from refining of oil. That would be the same oil some people like to call "Dyno".

Synthetic vs. Distilled would be a more apt description than "Dyno"

I have not been able to determine what precisely is the feed stock for synthetic oil yet. You will notice that that information is missing in the oil type descriptions posted.

[bbjumper]

After looking at everything I have come across regarding both it seems the only difference is that Synthetics with similar additive levels don't breakdown and maintain viscosity and lubricating ability over a longer period.

[bbjumper]

Another good read..

http://www.calsci.com/motorcycleinfo/Oils1.html

[mrbill5491]

I really like the color purple...