I have done some testing at cold climate. That summer grill block already block over 60% of the grill but even still the fully blocked is much faster
In this video similar setup than in previous video, but now I started to drive immediately.
Now the blue engine temp light stopped in 132 seconds from the start with summer grill block on (about 8 minutes when car running in standstill). After 5 minutes inside temp was already at 0 celsius (10 minutes when car running in standstill). after 10 minutes it was over 10 celsius. Next test will be with winter grill block. That summer grill block works fine up to -10 celsius but after that its too cold inside to take out the winter jacket and gloves etc.
Winter grill block.
In this warm up video I have installed Tuneko Lupo 3L winter grill block in place. Weather is -18 celsius and it takes 110 s to stop the blue light which means engine is at +5 celsius (summer grill block 130s and in standstill idle 8minutes).
zero celsius inside temperature is reached at 3 minutes and 27 seconds. +10 celsius is reached 6 minutes 28 seconds (it took ten minutes with summer grill block to reach +10 celsius)