I'm not convinced that Pentosin A1 concentrate is the same as the newer long/extended life Asian PHOATS that come as a premix in oem form and as ZAF after market. And also available now as PB OEM brand concentrate.
Toyota LL Red oem comes as a concentrate too, but is the older shorter interval phoat AF. It's recommended service interval according the OM is ~2years or 30k miles, whichever comes first. If one looks at A1 profile on pentosin.net, and limited to through 2004 Toyota vehicle, would seem to indicate it a clone or direct replacement for older Toyota Red LL.
That's said, according to Toyota SLL pink is compatible with older red LL and can be safely mixed.