I understand below to mean, good quality gas should be used but not necessarily that Top Tier members are the only companies producing high quality, detergent rich fuels. That being said, MARATHON gas stations are taking over several other stations (BP, Shell and Mobil) around here. Is MARATHON gas considered as good as the others in your estimation? I also use Techron every oil change. From both Hyundai owner's manuals Fuel Additives HYUNDAI recommends that you use good quality gasolines treated with detergent additives such as TOP TIER Detergent Gasoline, which help prevent deposit formation in the engine.