does not seal properly, sets engine code
I tried this locking gas cap on my 07 Chevy Colorado and it set an engine right away....same code as if the gas cap would have been left off. The treading of the cap looks quite different than the stock cap and it does not appear to get a good connection of the filler neck. I've used Stant locking caps on other vehicles with no problems, but this one is not worth buying for a Chevy truck.

An Investment That Pays For Itself MANY Times Over
With gas prices well over the $4.00 mark and news reports of gas thefts rising in record numbers on personal, government, rental, farming, and airline vehicles, this investment has provided peace of mind from the day it was received in the mail.

If you listen to critics, they will tell you that this is a deterrent that is a waste of money, because thieves will still find a way to siphon gas from an automobile by drilling underneath a gas tank, and taking the gas that way. Well, be that as it may, why not make it a little harder for the thief to hit your car?

By not buying a locking gas cap, it's kind of like a person reasoning that it's a waste of time to lock the front door to your home, because if a thief is going to come in and take your belongings, why make it hard for them?

I would trust no other brand of locking gas caps other than Stant, and would advise other car owners to look into purchasing one for each of their vehicles in the near future.

Bought this to prevent fuel theft (and possibly being stuck somewhere)
Fits 2005 GM Cadillac Escalade 2004 (non-screw type OEM).
In locked position, the cap free-spins. In unlocked position, the cap twists with the turn, opening the fuel cap.

The key only comes out in locked position (i.e. free-spin). This is a hassle, because I originally wanted to occasionally lock (e.g. parked in questionable neighborhood), and leave it unlocked most of the time. Now I carry both gas caps (OEM around home, and this locking one when I am on a trip).

Excellent product
I purchased this locking fuel cap for my 2008 Chevy Tahoe and it fits perfectly with no problems. Easily installed in minutes. I was able to install with original plastic tether.

Cheap "insurance"
As previously stated, you can go the Stant's web site to find the model that fits your vehicle. I found one for my 2008 Sierra (flexfuel) and it works great. It is easy to get on and off.