Oil ?

[drzewickid]

I know this has been beat to death but I have a quick question. Just ordered ZDDP and just changed my oil with Royal Purple. SHould I dump out the RP and just use conventional with the additive? Or just add it to the RP?
TIA

 

[1quick6]

Just add it. RP already has zddp in it and their xpr line has a higher concentration, something like 1500ppm.
Their website states not to add anything to their oil, but that's probably because they don't want the government going after them for telling people to add zddp to the vehicle.