to quote http://www.omegaowners.com/forum/YaBB.pl?num=1246444409
you would only likely need the 1litre if buying, but I would go for the 5, plenty for future topups then
sorry to say im getting it by the 20litre! and im only using 10-20% coolant
I think that weak a solution may bite you in the arse at some point 
4 x 5l is cheaper than 1 x 20l iirc. I have a K series. I buy LOTS of Vx Red 
The arse bite has occured already, hence the weak solution, going through over 1 litre a day, the head will be done before tooooo long.
dunno if the coreplug is leaking more than it ever did, or whether it is the HG as symptoms are different - i never find the car in a puddle this time.
I just want a little cooling and rust protection, when I do the gearbox in a week or 2 I should have a better idea
the 1998 3.0l HG is normally the back outside corner of the 2/4/6 bank 
be interesting to see where its going thats for sure.
radweld made a difference 1st time, not any more, so think a 2nd issue has arisen.
Easy enough to pop plenum off and pressurise it up a bit
aye, it is, ive a tyre valve and an old cap.
also got a leaky coreplug, ticking manifolds, and poss HG
gearbox getting swapped out asap, should be visible water at the back i reckon.
should do some smell tests on coolant tanks as well, really not sure mine is as pure antifreeze as it once was.