Sump plug, odd size?

[Owen_m]

The sump plug on my 1999 Clio 1.2 8valve appeared to be a 3/8th square drive; like on a ratchet or bar but my ratchet and 3/8th bar don't fit its slightly smaller.

Where can I get the tool for sump plug from? any ideas?

Thanks

 

[James28]

Halfords. Just trying to remember what size.
8mm
http://www.halfords.com/webapp/wcs/..._productId_198829_langId_-1_categoryId_255216

 

[Owen_m]

Nice one mate, was just a bit puzzled as all our engines in work (big diesels) have imperial square drive sump plugs.

Thanks