kevtherev wrote:you'll need to rethread the hole bigger with a suitable thread cutting taper tap, and get an M16 x 1.5 renault sump plug, or helicoil insert it and re-use std. sump plug. [M14 X 1.5 MM Pitch, if i remember right.]
MAFCO Part No 551-7140 Renault sump plug with washer M16 x 1.5 x 12 cost £3.95.
Looks like you've made up your mind but after the same thing happened to me I went for the M16 tap. I feel confident it won't strip again and now always use a torque wrench with copper compression washers. For some reason I just don't trust helicoils that much, plus if you don't shorten it you won't get all the oil out when drained.