I dilute my liquids all the time. If you do it 1:1 (16 to 8 in my case), it still has quite a flavour and is far from tasteless. Actually, taste seems to "evaporate" as you vape on, especially with refilled carts, also with undiluted liquids, so you definitely will not be losing much from the taste point of view, and saving (almost) half the money.
Also consider the fact that most of the dubious chemicals in our liquids come from the flavouring. So by diluting the 36 to 18 you also decrease possible harmful ingredients by half...
I'm definitely going to be diluting from now on, just as soon as I use up all four of my 18mg bottles.