I had the unfortunate experience of air con failure last summer on both the Leon and Ibiza due to impact by road debris etc. The holes in the lower grille's seemed to offer little protection against this, so i fitted some additional mesh to the inside of the grille's. There was no effect on coolant or oil temperature right through summer, including a very hot trip down to Italy. The mesh and cable ties were only a few quid so lets hope it offers a bit more protection! I have been looking at other car makes now (sad) and am shocked by the size of some of the grille holes, my next door neighbours Mercedes GLA has holes that big i swear a cat could crawl in! The only downside I've found up to now is it seems to collect bits of straw and leaves which need picking out.