I have just confirmed in the Specs
The T-Stat Valve starts to open over temperature 80-84C. And is fully open in between temperatures 95-97C.
This car needs to run at around 91C as the desired optimum temperature. This 87C figure, I am not sure myself, but this is what I remember was written over the valve as far as I remember. May be they write some aggregate figure because this is not a digital gadget and temperature really spikes up in these places and conditions within seconds.
A good synthetic oil is also made to do the best viscosity vs lubrication formulation at these temperatures. That is why they last long vs the minerals.
One more thing that is very important is that, you need to make sure that there is no air trapped in between the coolent supply, becuase the air gets trapped into the engine blocks and the temperature where there is air really shoots up very high as compared to where the coolent is touching the blocks. And this is really bad for the alloy at that point of contact and it can deform quickly.
The cars having deformed engiine blocks are the same cases, in which they blame the car specs that they get over-heated.