Regardless of terminology, Fast “Burn” or Activation Temperature, the concept is the same – ZDDP chemistry requires heat and load to initiate the chemical reaction that forms the phosphate glass film that provides the sacrificial anti-wear film.
With regards to the different types and names of Zinc (ZDDP, ZDP, ZDTP, etc…), they are just naming the variations of “Zinc” based anti-wear chemistry. I noticed one post about ZnDDP vs ZDDP. They are the same. Some old school chemists still use the “proper” chemical symbols when abbreviating a formula – Zn is the symbol for Zinc.
So what does all of this mean? Basically, the lower the activation temperature, the faster the “Zinc” reacts. While this is good for wear protection, it does come at a price – shorter drain intervals and shorter catalytic converter life in mineral based motor oils. When the “Zinc” reacts it releases Phosphorus compounds. Some of these form the Phosphate glass like film film that protects your engine, but some of these Phosphorus compounds get sucked out of your crankcase by the PCV system along with the oil vapor created by high temperatures on the pistons and cylinder walls. These oil vapors and Phosphorus compounds are pulled thru the PCV system into the intake and out the exhaust system where they react with the catalyst inside the catalytic converter. This is why the API licensed oils have both reduced Phosphorus content and volatility over the last few API service categories – increased protection for the emissions system equipment. Lowering volatility reduces the rate at which the motor oil produces oil vapor, which keeps the motor oil in the crankcase and off of the catalyst. Same with less reactive “slower burning Zinc” – it keeps more of the Phosphorus from the ZDDP in the crankcase and off the catalyst. These changes have enabled the OEM’s to extend the life of catalysts from approximately 80,000 miles up to 120,000 miles.
The trade off for this is less Valvetrain protection with larger lift cams and higher valve spring rates. These more aggressive engine designs need the “faster acting” ZDDP. Our testing and experience with Lubrizol confirms this. The more aggressive the Valvetrain, the more aggressive you must be with the anti-wear balance in the formula.
A stock Valvetrain is fine to run on an API licensed oil, but a modified Valvetrain will require a different anti-wear balance. The exact use of the application – how you use the car and service the engine – will determine the appropriate additive balance for that application. For example, a modified engine that only races will use a high moly content and very low detergent package. This allows for maximum activation of the ZDDP and function of the Moly. This is important because the sustained high RPM and temperatures of racing conditions demand it. The price for this is shorter drain intervals.