[Radek]

I have parsed cre.bif and found the following:
Jim is right. Minor corrections and additional info:
1. Brain Golems aren't immune to slashing (they have 25 against slashing). I can confirm it. Mordekainen Swords are able to kill Brain Golems.
2. There is no actual difference between Adamantine and Iron Golems. They differ only in weapon resistances. Adamantine golems have 90 against all weapons, Iron Golems have either 75 against all weapons (De'Arnise Keep, Windspear Hills) or only 20(!) against all weapons (Suldanesellar).
3. Iron and Adamantine Golems have 125 against fire (both magical and non magical). In the other words, fire heals them. Do not use fire based spells and weapons with fire attack against them!
4. Lesser Clay Golems and Flesh Golems have 125 against normal cold but no resistance to magical cold(?!)
5. The only kind of golems that is IMMUNE to certain weapons is the Clay Golem. The golem has 100 against piercing, slashing, and missile. Other golems are more or less resistant to weapons but they are not immune.