Hi there,
hope you are enjoying the weather here in the UK?
However, just a thought, you said you needed to add coolant, does that mean the rad was rather low on water. If so, wouldnt it be a wise idead to fully top up your system?
This would mean using an empty 2ltre lemonade bottle taped to the top of the rad and bleeding the system via the bleed screws on the rad and the one near the a pipe leading into the block. Dosnt take long and would give you piece of mind.
Just a thought.
Andy