Car in question: 1991 Firebird, V6
Problem: The oil filler cap will not come off. It just turns and turns in both directions. Any ideas on how to get this sucker off?
Remove the valve cover, smash out the old cap, and install a new cap.
Tester
I don’t think you’ll have to take the valve cover off. If it’s plastic, you can break the cap with a pair of channel lock pliers. Be careful that no pieces fall into the engine. If it’s metal, it may not break up very well. Of course you’ll want to have the new one on hand before you break it. I’ve done them on Chryco products, and assume the Firebird will be the same.
If you do take the cover off, you probably won’t have to smash anything, but have the new cap ready to go on unless you have another car.
Out of curiosty, is this the first time you’ve tried to get the oil cap off? The reason I ask is that the oil cap in my 01 Impala doesn’t screw off, you turn it about half a turn then just pull it off. Seeing as the Firebird is also a GM product, I wonder if it has the same style of cap.
Of course, if it normally screws off, then, well, follow the advice from the other posters.