does any one know the size of the o-ring that goes in the s5 radiator filler neck my local sutozone has like billions but ive gone threw three and there all still to big (thats what she said) i think mazda trix sells them but im not evenc sure i know what its called.

 

drive the car over there.Get the Counter guy to grab a mitt full and Size it up.

 

http://www.mazdatrix.com/getprice.as...m=15-1740-N326

I want to say it's 18mm, but I can't remember exactly what size I used. I have a whole tray of hundreds of o-rings, so I just found the best fit.