Quaker State Defy & Zinc Additive

[KevinV]

Here is more technical question. On a Corvette forum, it has been indicated that the zinc additive in Defy is merely zinc rather than zinc with phosphurs (the zinc would be coating phosphorus and carrying the phosphorus to key engine parts (like tappets). Is this true ? The suggestion on the Corvette forum is if it's just zinc it does not do any good for the engine.

Overall, how does Defy stack up to MaxLife or Castrol High Mileage ?

 

[Ken2]

That sounds like nonsense.

The zinc dialkyldithiophosphate is not metallic zinc and not elemental phosphorus. It is, "a family of coordination compounds invented by Castrol that feature zinc bound to the anion of dithiophosphoric acid. These uncharged compounds are not salts. They are soluble in nonpolar solvents, and the longer chain derivatives easily dissolve in mineral and synthetic oils used as lubricants."

http://en.wikipedia.org/wiki/Zinc_dithiophosphate

ZDDP and its related compounds are excellent antiwear and antioxidation agents, but there are others that do the same job (or a better job in combination with ZDDP) but at higher cost. For some reason, worshiping ZDDP has become almost a religion.

Here's what Shell says about their Defy:
http://www.epc.shell.com/Docs/GPCDOC_X_cbe_24855_key_140007079157_201203220840.pdf
Note that they call it "zinc" but it is surely in the ZDDP family of antiwear compounds. Just about everything else they mention sounds like marketing garbage to me; "...extra anti-wear additive to help protect against the
wear stresses your high mileage engine experiences in everyday driving...." Baloney.

 

[CATERHAM]

Zinc and Phosphorus are part of the ZDDP molecule so you can't get one without the other although I believe there are some other uncommon sources for P.
And yes it is true that it is the P that is the primary AW element so the Zn is just going along for the ride.
So yes it is the concentration of P that you want to focus on.

 

[KevinV]

Thank you. You guys' level of knowledge always impresses.

 

[Ken2]

Quote:
the P that is the primary AW element
And the sulfur, the "thio" in zinc dialkyldithiophosphate, is necessary to bond the phosphates to the iron.

 

[buster]

Interesting. I'd like to know more about this oil. A great value at $4.44qt. Great for flat tappet came engines.