I think you will get varied opinions on this one. I haven't put a locking cap on mine, yet. In some ways I think it is better to let them siphon some gas rather than drill or punch a hole in my tank or tap into the main hose. The tank is very easy to access underneath the rig so it's easy to see that if someone wanted it bad enough there is no telling what they would do to get it. Then there is the law of large numbers - if your rig is stored at a "secure" facility with 400+ other rigs - what are the odds yours will get hit?
I have a locking gas cap on my toad - so go figure!
Bubba & Chiquita + Two Vizslas (Barley and Sophie)
2008 Georgetown 315DS SE LTD
2011 Jeep Wrangler Unlimited Rubicon
Sterling All-Terrain Tow Bar - SMI Stay-In-Play Duo
Do What You Like - Like What You Do!