My Nissan's service manual actually calls for Dextron III ATF for the power steering system.
I recently had my PS pump replaced. The mechanic would not guarantee his work unless I agreed to leave in the Valvoline Syn Power he had used for the job.
His focus was on the providing what he believes to be the better protection against the friction occurs in the PS pump, Valvoline Syn Power.
He highlighted the better lubrication and the longer longevity of Synthetic PS fluid over the Dextron III ATF.
While my concern was the seals that had always been conditioned by the Dextron III ATF, which is required by Nissan for my vehicle's PS system.
Extra Info:
Nissan dealership parts counter manager told me that Nissan my car requires "Nissan Power Steering Fluid", which supersedes the "Nissan MATIC-D" ATF that Nissan technicians previously used after Dextron III was no longer available, as both MATIC-D and Nissan PS Fluid contain Dextron III.
(Nissan began selling the Nissan brand PS fluid began in 2011. part number: 999MPAG000P)
Now, because my car's PS system required flushing to remove metal flakes in the fluid from the bad, growling, old pump, if leaks occur anywhere in the PS system, his understanding is that because the seals in the steering rack are old to begin with, any leak that might occur in the future would be due to the condition of the seals and not attributable to the fluid he elected to use in place of what was specified to use by Nissan.
I found it noteworthy, one, that the Nissan engineering department responsible for the service manual specified using Dextron product in their PS system, even when Synthetic fluid was available, and two, that today Nissan dealership technicians continue to use the Dextron III (Nissan PS Fluid) product for my car's PS system in place of any Synthetic PS fluid.
