Steve,,a tad away from what you are looking for, but a while back, the Hybrid (V8 auto) always gave be cooling problems etc,,
Tried a kenlowe, with not a lot of success !! and even they say in the small print, to refit a viscous if you are going to work the vehicle hard, ie towing, etc !!
I cured mine with a pair of Mondeo a/c fans, and Si's, X-fan switch/housing etc,
As i have very little space behind the rad, the cowing was trimmed down, and now it will tick over all day and the temp will not move,