What's the heaviest gauge string i can put on my 6 string guitar?

The thickest strings I know of a guitarist using were .16's . The guitarist was Dick Dale. I don't know if he still uses that gauge or not though.

Hello there, There is a lot of confusion about the Starcaster. Originally that was a semihollow body electric guitar from the late 1970s. In the 1990s Fender reused the Starcaster name for a line of inexpensive acoustic and electric guitars that were sold through stores that were not Fender dealers (big box stores). Quite recently Fender has made a reissue of the original Starcaster. So when you say you have a Starcaster, people do not always know what you mean. I assume you have one of the inexpensive acoustic or electric guitars with the Starcaster name. If you have an acoustic, I will pass on the heaviest strings you can use. I leave that to the guys who regularly play the acoustice. If you have one the Starcaster electric guitars (made to look like a Stratocaster), 11s are as heavy as you should go with it. I don't know how heavy a set of strings you can put on a Fender Stratocaster. I have one with 16-65 on it.Manufacturers only make matched string sets up to 13s. Above that you have to assemble your own set of strings. As you increase the string size, you increase the string tension (if tuned to the same pitch). That means the strings pull more on the neck and on the tremolo bridge. With heavier strings on your guitar, you will have to adjust the neck relief and set the action. You will have to adjust the intonation. You will have to adjust the tremolo spring tension to equal the increased string tension. All of that will be needed if you increase the string size more than 1 size up. In other words, you need to do a complete set up on the guitar for it to be playable. I would not use 13s and probably would not try 12s (if you plan to tune to standard pitch). The hardware on the Starcaster is not as good as on the Fender Stratocaster. I am pretty sure the screws will strip out of the wood under the pull of 13s. 12s is iffy. 11s should be safe to use on a Starcaster. But you will need to do a complete set up on the guitar for it to be playable. Talk to you later, Norm

I'm guessing you mean a newer Starcaster, at least I hope so. That guitar would have been setup with 9's so putting a heavy gauge on it will require a setup for sure. Also understand that with 13's or heavier, bending will be very difficult. Your nut will probably need to be re-cut also.

You can put on as heavy a gauge as you can find, so long as they are intended for six string guitar. I'd be wary of doing anything extreme to a real Fender Starcaster as they are quite valable vinage guiars now.