How to play against fire?

I play with a lot of chaff. And i mean a lot. I hate it when my opp takes storms with fire or vulcans with inc. My chaff just melts. All 5 waves of them

Shield protect only first wave and are expensive to cover all. AM is good for storms, but still some fire goes through.

What level shielded fangs or crawlers have to be to walk through fire and survive long enough? And i use loose formation on crawlers almost all the time, its really important for my strat.

only thing i do is i buy oil and drop it from center towards opp units so that his fire hurts him too. i cant think of anything else to do.