GS LC topping up coolant

[DANE]

What sort of antifreeze (apart from OEM stuff)?
I thought there were different types, and if you cross mixed them, the result was jelly !!

Two general types, MEG Mono Ethylene Glycol (general antifreeze) or PEG Poly Ethylene Glycol for specialist applications (e.g. food production applications) - best get a correctly rated product with appropriate inhibitors specific for the vehicle.

The amount you will need is tiny maybe 20-25 % of the whole cooling water volume so maybe cadge some from a dealer (take your own clean bottle).