Originally Posted by Oldswagon
So is there a OTC dino that would work well for an old flat tappet engine? In my case this is a high mile engine that only sees summer use. I have been using Rotella because it was cheap, good quality and most on BITOG seem to recommend HDEO for these types of engines.
Rdy4War, what do you mean the ZDDP types are different?
The GP1 looks like good oil, but I am not sure if I can find it in Canada. And while I use Mobil 1 in my modern cars, for the usage this engine sees I think synthetic is overkill.
I will be building this engine down the road, and at that time it will be getting a roller cam.
There are three main types of ZDDP: primary, secondary, and aryl, with various sub-types within each. Primary types are less reactive and less effective at wear protection, but offer greater anti-oxidant properties and are less harmful to DPFs, cats, and other emissions equipment. It's the type used in diesel oils since at least the early 80s and suits a diesel engine that lugs a heavy load along at 1500 rpm for hours unend. Most gas oils use a blend of primary and secondary ZDDP, usually 60-80% secondary, in order to get greater reactivity at lower temperature and pressure. This benefits the short trips and frequent starts and stops seen by gas engines.
Your boutique options like Driven oils, Red Line, Schaeffer's, Amsoil Dominator and Z-Rod, etc... use all secondary type ZDDP. A downside to ZDDP though is that it increases hydrodynamic friction by way of its very function. If you load the oil up with too much ZDDP (regardless of type), you can increase that friction to the point that it becomed abrassive. My understanding is this occurs at around 1900 ppm Zn and up. This is why I now like to use the least amount of ZDDP that is absolutely necessary for sufficient wear protection, as well as a good dose of MoDTC friction reducer.
