'reaches over.... under some old performance VW..... haynes manual'
Good old haynes

"Ethylene gycol-based antifreeze with corrosion inhibitors"
and the system takes 6.3 litres, but make sure to drain the old stuff out first, dont forget the matrix as well, I flushed mine out with a hose till the fluids cleared. Then add your 50% anti freeze (Or what ever is recommened) and then top up with water as described in other threads about bleading the coolant!