verslagen1 wrote on 01/02/11 at 09:04:07:It's an odd size...
Both plugs are the same size and thread m12x1.25
same as oil drain plug, the plug up top and the sparkplug.
Smart. A manufacturer would only need one size tap on the line for the big holes. If they were all 3 different sizes, then thered be 2 more inventory items to buy & keep stocked.