I had posted in the Little River section asking about E free gas for that area. Here is the information I have found based upon limited web searches.
I hope this helps someone. If you know of any others, please add to what is here. They have GPS numbers listed if you need those.
Charleston EXXON 89 John Clair’s Exxon 334 Folly Rd. N32.75988 W79.97431
Charleston UNBRANDED 93 Piggly Wiggly 1985 Folly Road N32.68607 W79.96116
Charleston EXXON 89 Russell’s Exxon 2209 Savannah Highway N32.79113 W80.03835
Charleston UNBRANDED 89 V GO 1127 Savannah Hwy N32.78388 W79.99681
Garden City SUNOCO 93 Bull Mart #4 2464 Highway 17 S N33.57108 W79.03135
garden city/myrtle beach SUNOCO 87 89 93 sunoco Business highway 17 south N33.60818 W78.96967
Georgetown UNBRANDED The Ice House 330 N. Fraser St. N33.37551 W79.28768
GEORGETOWN EXXON 89 SEA STORE EXXON 1200 CHURCH ST N33.37432 W79.28403
GEORGETOWN UNBRANDED 89 South Island Bait House 7113 South Island Rd. N33.27195 W79.29912
Murrells Inlet UNBRANDED 87 West Oil Company Inc 4584 Highway 17 Bypass
North Charleston EXXON 93 Mizzell’s Exxon 5998 Rivers Avenue N32.90601 W80.02149
Pawleys Island UNBRANDED 91 Pawleys Island Supply 10460 Ocean Highway N33.43834 W79.12746
These are from Pure-gas.org website.
Another website lists Dock Holiday’s Marina and Harborgate Marina in Myrtle Beach.