Bought a new 2013 GMC Sierra 1500 4X4 WT with the 4.8 L flex fuel engine. Cant find a locking gas cap for it. Not really worried about someone stealing gas, just don't want some punk putting anything in my gas! Everytime I think I`ve found one that fits, I find out it wont. I thought about a locking fuel door, but don't really like the way it looks, might have to be the way I go. Is it "too early" for after market things like this? I`ve looked on the Stant web site and they say the 10504 fits, but it doesn't fit the 'flex fuel" models and the 10504Y flex fuel cap is threaded.
Thanks for any info.

On rockauto I see a cap listed, STANT Part # 10504
I'd try to find that cap at a local auto parts store, and be sure it fits, because I see a non locking Stant cap listed, and it does not have the exact same specs listed.

I'll post the specs for both below so you can see what I am talking about.


Non Locking Stant Cap
#11834} OE Equivalent Fuel Cap; 2 39/64" Emission Control (1 49/64" x 1 25/32" Threaded)


Locking Stant Cap
#11504} Regular Locking Fuel Cap; 2 29/32" Emission Control (1 49/64" x 2 31/64" Threaded)

Just an update, bought a locking gas door. Was an easy install and looks great. Talked to a buddy of mine that runs a private repair shop. He said that I will be throwing codes and its not worth it. So I took his advice and I`m glad I did.

Thanks for the update, did you end up going with the Stant locking cap #11504

No, still have factory gas cap on. Just took off the factory gas door and bought a aftermarket locking fuel door. Was an easy install, hardest part was drilling out the rivets on the factory door to remove it. But it wasn't that hard. My Sierra`* color is Quicksilver and I went with a brushed aluminum door, looks great!!!! And now I wont have to worry about anyone "adding" anything to my tank. I wished GM would go with a system like Toyota has, my wife'* Camry has a locked fuel door that you release from inside, great idea I think!

Ahh ok, glad the installation of the door was easy.
If you ever have to replace the gas cap for any reason, the Stant caps I listed in post 2 of the thread should not bother the EVAP system, both caps had emission control listed on both, so they should not cause any codes to be thrown.

Thanks for your info!!!!

Just a quick update on my locking fuel door,,,,alittle FYI. Bought a RPB locking fuel door, chrome. Install was easy and it looks great, one problem,,,,,first time it saw alittle road salt, it pitted! Pitted bad! I even put a coat of Mothers wax on it BEFORE I installed it. So, now I`m going to have to replace it in the spring with I don't know what because its now going to rot out! Probably put the original door back on. Not happy, guess you get what you pay for!

It sucks that it got pitted on you, road salt is some nasty stuff.
Hope you eventually find a satisfying fix.

use the lock mechanism on the stock door