So. I f'd up one plug. Don't ask how. I don't want to talk about it. I'm running NGK iridiums in a 89 turbo. I can't get a new one for a couple days. Would it be horrible to use one different plug for a few days?
To MHO, I don't think it would matter, just make sure the plug is good (not cracked/chipped/burnt) but make sure the gap is correct and just use that. It won't make that much of a difference if you're using one that's platinum, copper or iridium.
The only difference is that coppers conduct well but have a short life span, platinums last 100,000 km but conduct less than coppers, and iridiums conduct well and last 100,000 if not more.
Don't worry, I mixed platinums with a copper one and I was good till I bought the platinum.