Although a timesert is a more self locking insert, I've never had an issue with helicoils and I've used them in numerous drain plugs. If you have to buy a kit anyway, there may not be any more than 20$ in price difference to get a timesert kit. Plan on spending 50-70$ to repair this and a new plug. If you don't fix it right, you could have bigger issues down the line.
Put grease on the drill/tap and tools and keep cleaning them off, then I'd flush with a little diesel to be sure it was clear.
All our government does is distract us while they steal from us, misspend our tax $ and ruin our country