Absolutely not especially for winter driving. The Vanagon has so much excess cooling capacity that the radiator needs to be completely closed off for a quick warm up. If you really want to get the effect of this just leave the bled bypass on top of the thermostat housing open and you will have the full time bleed that the hole will provide. The importance of full closure is such that the version F has rubber seal on the main disc. 

Dennis
  

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of Dan N
Sent: Monday, September 7, 2015 10:26 PM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Replacing Thermostat... and gas mileage

hi Dennis,

some said it's good idea to drill a small hole (1/8") on thermostat disk...
what do you think?

thanks

dan