I recently had a radiator preventive maintenance check. I had a lavramon flush.

Mechanic told me to buy a brand new radiator because the head assembly is already cracked.

Brand new radiator is around P3,900 (civic). He also told me to buy a new thermostat and new radiator cap. I told him it never overheated for such a long time, why replace something not broken? He told me there is always a risk of overheating so it is best practice to change everything because it's a new radiator. Everything must be replaced as a set. He also told me never to flood the reservoir. There is a max level indicated on the reservoir. If I want to top up, it should be at that max line only.

I hope this helps you.

OT: Since you have a 97 civic, have you changed your timing belt already? You should be worried if you haven't as it can break anytime and destroy your valves. Timing belt change includes the water pump, tensioner and two oil seals. While at it, have your valves adjusted as well.