I fill to a 1/4" or maybe a bit less in the neck. Anymore and it will puke. So I would say yours is normal & self-correcting. Geo On Mon, Feb 27, 2012 at 9:23 AM, <wbeech at flash.net> wrote: > ...a modest amount of overflow after only 20-30 minutes of driving. I try > to > keep the coolant level at about 1/2 the depth of the extension neck...