thankyou to all in advance for helping me fuel my filthy obsession with landrovers and in particular my '76 series 3 which i am learning how to a/ drive b/fix and upgrade i live in the new forest and am a fairly compitent diy mechanic famous last words,........collybobs

after flushing my rad on a series 3 1976 and draining it only five litters of cooland and water 50/50 would fit back in do i need to run the engine until its warm? thanks:)