Here’s what’s inside each bottle, how they perform in real marine fuel systems, and which one belongs in your tank.<\/p>\n
![\"Heet](\"https:\/\/scontent-hkg1-2.xx.fbcdn.net\/v\/t39.30808-6\/556966301_31480833208230104_4227547104600486018_n.jpg?_nc_cat=107&ccb=1-7&_nc_sid=0327a3&_nc_ohc=sO2Uk85U3FgQ7kNvwFozU8E&_nc_oc=Ado1dWfcIAJ3GYaz0zEmtv9B_t1M2bC94oJVZv9GPaSLx6FW-7J8mYNaRdtX3nUn9Bs&_nc_zt=23&_nc_ht=scontent-hkg1-2.xx&_nc_gid=FGczK6ytfoWinj1Og-1b_w&_nc_ss=7c289&oh=00_Af0K4F8sBJ3SYT8yJM-VkBfqDeQmiRxNfZKomMQmflo77g&oe=69F64A49\")
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What’s Inside Each Bottle<\/h2>\n
The chemistry is simple. Heet \u2014 the yellow bottle \u2014 runs on methanol<\/strong>, also known as wood alcohol. Iso Heet \u2014 the red bottle \u2014 uses isopropyl alcohol (2-propanol)<\/strong>, the same compound found in most rubbing alcohol.<\/p>\n One ingredient separates them. That difference has real consequences for your marine fuel system.<\/p>\n Both alcohols mix with water. But they behave differently once they’re inside your tank.<\/p>\n Heet (methanol)<\/strong>: Can phase separate<\/strong> with water present. It splits from the fuel under certain conditions. You’re left with a contaminated, layered mess instead of a clean solution.<\/p>\n<\/li>\n Iso Heet (isopropyl alcohol)<\/strong>: Resists phase separation<\/strong>. It stays blended with the fuel \u2014 even after the tank sits idle for weeks.<\/p>\n<\/li>\n<\/ul>\n Iso Heet has a lower density (0.786 g\/ml vs. Heet’s 0.792 g\/ml). That lets it sink toward the tank bottom \u2014 the same spot where water collects through condensation. So it targets the problem right at the source.<\/p>\n Methanol attacks rubber.<\/strong> Older marine engines use rubber fuel lines, O-rings, and seals. Methanol degrades those components over time. Iso Heet doesn’t carry that risk.<\/p>\n The price difference? About $1 per bottle<\/strong>. For a marine engine, that’s an easy call.<\/p>\n Flip the bottles around. Read the fine print. The labels look almost identical \u2014 same brand, same shelf, same general promise of protecting your fuel system. But what’s inside is a completely different story.<\/p>\n Here’s a side-by-side look at how they differ in real use:<\/p>\n Yellow Heet (Methanol)<\/strong><\/p>\n<\/th>\n Red Iso Heet (Isopropanol)<\/strong><\/p>\n<\/th>\n<\/tr>\n Core ingredient<\/strong><\/p>\n<\/td>\n Methanol (99%)<\/p>\n<\/td>\n Isopropyl alcohol<\/p>\n<\/td>\n<\/tr>\n Fuel compatibility<\/strong><\/p>\n<\/td>\n Standard gasoline only<\/p>\n<\/td>\n All gasoline types, 2-cycle mix, diesel<\/p>\n<\/td>\n<\/tr>\n Primary function<\/strong><\/p>\n<\/td>\n Gas line antifreeze, water removal<\/p>\n<\/td>\n Water removal, injector cleaning<\/p>\n<\/td>\n<\/tr>\n Burn behavior<\/strong><\/p>\n<\/td>\n Clean burn<\/p>\n<\/td>\n Produces visible soot<\/strong> \u2014 even diluted 1:4<\/p>\n<\/td>\n<\/tr>\n Open stove use<\/strong><\/p>\n<\/td>\n Compatible<\/p>\n<\/td>\n Not recommended without special porting<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Iso Heet costs about a dollar more than standard Heet per bottle. One outboard repair \u2014 a fuel system clog, a damaged seal, a carburetor rebuild \u2014 runs $500 to $2,000<\/strong> depending on the engine and the mechanic.<\/p>\n That’s not a comparison. That’s arithmetic.<\/p>\n Category<\/p>\n<\/th>\n Iso Heet (Red)<\/p>\n<\/th>\n Heet (Yellow)<\/p>\n<\/th>\n<\/tr>\n Active ingredient<\/strong><\/p>\n<\/td>\n Isopropyl alcohol (isopropanol)<\/p>\n<\/td>\n Methanol<\/p>\n<\/td>\n<\/tr>\n Water absorption capacity<\/strong><\/p>\n<\/td>\n 5x standard antifreeze<\/p>\n<\/td>\n \u0623\u062f\u0646\u0649<\/p>\n<\/td>\n<\/tr>\n Phase separation risk<\/strong><\/p>\n<\/td>\n None<\/p>\n<\/td>\n Present under certain conditions<\/p>\n<\/td>\n<\/tr>\n 2-cycle engine safe<\/strong><\/p>\n<\/td>\n \u2705 Yes<\/p>\n<\/td>\n \u274c No<\/p>\n<\/td>\n<\/tr>\n Diesel compatible<\/strong><\/p>\n<\/td>\n \u2705 Yes<\/p>\n<\/td>\n \u274c No<\/p>\n<\/td>\n<\/tr>\n Rubber\/seal safe<\/strong><\/p>\n<\/td>\n \u2705 Yes<\/p>\n<\/td>\n \u26a0\ufe0f Risk of degradation<\/p>\n<\/td>\n<\/tr>\n Year-round use<\/strong><\/p>\n<\/td>\n \u2705 All seasons<\/p>\n<\/td>\n Winter antifreeze use only<\/p>\n<\/td>\n<\/tr>\n Price premium<\/strong><\/p>\n<\/td>\n ~$1 more<\/p>\n<\/td>\n \u0627\u0644\u062e\u0637 \u0627\u0644\u0623\u0633\u0627\u0633\u064a<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Boat forums don’t debate this much anymore. Iso Heet is the go-to choice for outboards, inboards, and anything running a 2-cycle mix. Isopropanol handles marine water contamination better. It stays stable in fuel that sits between trips. It also skips the material compatibility risks that make methanol a real liability in a marine fuel system.<\/p>\n Yellow Heet has its place \u2014 in your car, in cold-weather automotive use, in a 4-stroke gas engine that stays away from water. That place is not your boat.<\/p>\n Fiberglass tanks crack from the inside out. Rubber lines don’t warn you before they fail \u2014 they just give way. These are the parts boat owners worry about most. So before you pour anything into your fuel system, you want to know it’s safe.<\/p>\nHow Each One Handles Water<\/h3>\n
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The Compatibility Problem Nobody Talks About<\/h3>\n
What’s Inside the Bottle: Iso Heet (Red) vs Heet (Yellow)<\/h2>\n
What the Comparison Table Won’t Tell You Up Front<\/h3>\n
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\n \n<\/th>\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n ![\"Heet\"](\"https:\/\/scontent-hkg1-1.xx.fbcdn.net\/v\/t39.30808-6\/558746773_31615167121463378_1948239304345921300_n.jpg?_nc_cat=105&ccb=1-7&_nc_sid=13d280&_nc_ohc=_XxxuKbUl7UQ7kNvwGHwNcw&_nc_oc=AdqLb-Byi0P9J4ZONAZUyMP0L7-8nFEC9tJtdB06KK_EKj90hY1CJ8Y42sXlbkpB25A&_nc_zt=23&_nc_ht=scontent-hkg1-1.xx&_nc_gid=xJnnj-veIy24_cHr2lg5tg&_nc_ss=7c289&oh=00_Af3_NWsTHUasGaFHCynXpFTqTnbEm-JMV24r2kUHuzxfYw&oe=69F62BE4\")
<\/p>\nThe $1 Calculation That Pays for Itself<\/h3>\n
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\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n The Verdict<\/h3>\n
Is Iso Heet Safe for Fiberglass Fuel Tanks and Rubber Fuel Lines?<\/h2>\n
![\"Heet\"](\"https:\/\/scontent-hkg1-2.xx.fbcdn.net\/v\/t39.30808-6\/557635578_31615059748140782_8765400473200274567_n.jpg?_nc_cat=103&ccb=1-7&_nc_sid=13d280&_nc_ohc=Pg6GtY1091AQ7kNvwGHIule&_nc_oc=AdpcuIMwjrJ6ECjibRTTmzyfbapjSeTjql00s9R76_Bxn7mkQqhbOOROaPKsqFcG1rI&_nc_zt=23&_nc_ht=scontent-hkg1-2.xx&_nc_gid=PIlZLJ9-HKWGQ1TdF0GPtQ&_nc_ss=7c289&oh=00_Af3iNPq4YSR16TBV0jtNkZMWI9F-cRB5hmYvBAld6CWt5Q&oe=69F63E6A\")
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