*TS

Your car seems to have the stock radiator top, that is made out of plastic. You would need a radiator cap with the smaller "nipple" with a rating of 0.9. You can purchase these at Denso shops (price is a bit high but this is a Denso original part)

Some Rollas have modified radiators, having copper tops instead of plastic. There was a time where you could just replace the plastic top (or bottom) at Denso but these particular parts are rather hard to find. Nowadays if an owner would prefer to replace their Rolla's radiator top with original parts, he would have to purchase the entire radiator which costs 17K.