I know this is an older post, but these questions seem to come up frequently. Doing a search takes me to results mainly saying this oil is made by Citgo. I have seen post where Rural King customer service has even suggested it is Citgo oil. I have been running the RK branded (when it was still being sold), Warren Lubrigold (when they were selling it) and the Harvest King for the last 4 years. The 1qt jugs of all of the above have (had) the "WU" Warren Unilube on them. This is not on the 5qt jugs, but I don't recall it ever being on them. It would seem unlikely that the 1qt are Warren and the 5qt Citgo. Wouldn't it? Pic below is 0W20 just purchased today. My partial 1 qt bottles of 5W20 and 5W30 also have the "WU" symbol.
Put this oil in my Tundra 5W-30 and my wife's Infiniti 5W-20 couple ago and both developed oil leaks within the first month. Drained it out put Mobil 1 back in, I normally run it in everything and my wife's car stopped leaking just a few days later. But' I had to change my valve cover gaskets out on my Tundra to stop my leaks, both sides too btw.
Idk why it made them leak but it sure did and just tightening down did nothing. Also it caused my tractor (Kohler Magnum) to seep oil around the head gasket halfway through the season and I had to change its gasket. Coincidence?
My guess is it turns to water when hot but idk that? Always liked my RK products but I lost big on this deal.. All the oil + my cost/time for gaskets. At least installing the new gaskets was easy for me, harder to do that on the Kohler than on my Tundra..lol.