In my opinion I think my cap with the O-ring is the only one that completely seals the tank . You can have a full tank of gas and go around right hand corners all day with no worry of the usual stain coming down your quarter panel .
I have been selling these that I have been making for a few years now.
http://www.ebay.com/itm/271152013666?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649
My O-ring gas caps will stop the spilling after you fill up and make a right hand turn .
http://www.ebay.com/itm/271055351394?ssPageName=STRK:MESELX:IT&_trksid=p3984.m1555.l2649
No , the lines you see are left when the CNC changes direction , they are very very slight and polish out with a Scotchbrite pad or fine sandpaper . I need to post a pic on the ad of the ones that are polshed .
Steve
I have one that I produce , it uses an O-ring for better sealing .
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=270570689013&viewitem=&sspagename=STRK%3AMESELX%3AIT
Thanks,
Steve