Fuel Siphoning & Storage

Part of Priority Salvage List

Every abandoned vehicle is a fuel depot. A typical car holds 40-60 liters of gasoline; a pickup truck holds 80-120 liters; a commercial truck holds 200-400 liters of diesel. In the weeks after collapse, millions of liters of fuel sit in tanks across any urban area, slowly degrading. Knowing how to safely extract and store it extends your operational window by months.

Where to Find Fuel

Passenger Vehicles & Trucks

The most abundant and accessible fuel source. An average suburban street with 20 cars holds roughly 1,000-1,500 liters of gasoline. A single parking garage can contain tens of thousands of liters.

What to expect:

• Passenger cars: 40-70 liter tanks, mostly gasoline
• SUVs and minivans: 60-100 liters, gasoline
• Pickup trucks: 80-135 liters, gasoline or diesel
• Semi trucks: 300-600 liters, diesel
• Delivery vans: 80-120 liters, gasoline or diesel

Finding the fuel door: Nearly always on the rear quarter panel, driver or passenger side. Look for a small door or cap. If locked (electric release), use a flat screwdriver or pry tool to pop the door. The actual gas cap may require twisting counter-clockwise.

Check before you siphon: Fuel gauge on the dashboard tells you if the tank is full, half, or empty — but only if the battery still has charge. Turn the key to “accessory” (one click, do not start the engine). If the gauge shows empty, move on.

Fixed Tanks & Depots

Gas station underground tanks hold 10,000-40,000 liters each, typically with 2-6 tanks per station. The problem: without electric pumps, extraction requires a manual pump with a hose long enough to reach the tank bottom (3-4 meters below ground). The fill ports are usually metal caps on the ground near the pumps. A wrench or pry bar opens them.

Gas Station Tanks

Lowering anything that could spark into a fuel-vapor-rich underground tank is extremely dangerous. Use only non-sparking tools (brass, aluminum, or plastic) near fill ports. No flashlights with exposed switches. No friction from steel on steel.

Farm bulk tanks: Farms with equipment often have above-ground diesel tanks (1,000-5,000 liters) with gravity-fed or hand-cranked pumps. These are usually unlocked and clearly visible. Diesel from farm tanks is often dyed red (tax-exempt) but otherwise identical to road diesel.

Heating oil tanks: Homes with oil furnaces have 275-gallon (1,040 liter) tanks in basements or alongside houses. Heating oil is essentially diesel (#2 fuel oil). It works in diesel engines, generators, and oil lamps.

Backup generators: Commercial buildings, hospitals, cell towers, and data centers have diesel generators with dedicated fuel tanks (500-10,000 liters). These are often in locked enclosures but accessible with a crowbar.

Alternative Fuel Sources

Propane — BBQ tanks (9 kg / 20 lbs), forklift tanks (15 kg / 33 lbs), residential tanks (120-500 gallons). Propane is stable indefinitely in sealed tanks. It powers stoves, heaters, generators, and some vehicles. A standard BBQ tank provides roughly 20 hours of grilling or 40 hours of low-heat cooking.

Kerosene — hardware stores, farm supply stores, home heating tanks. Excellent lamp fuel, heater fuel, and fire starter. Shelf life: 2-5 years properly stored.

Denatured alcohol/ethanol — hardware stores (as solvent), liquor stores (high-proof spirits work as fuel). Burns clean. Useful for camp stoves and as a medical antiseptic.

Biodiesel feedstock — restaurants have used cooking oil in grease traps and disposal containers. With processing (methanol + lye catalyst), this becomes biodiesel. See Vehicle & Machinery Cannibalization for engine considerations.

Siphoning Techniques

Gravity Siphon Method

The principle: liquid flows from a higher point to a lower point through a tube, as long as the tube is filled with liquid and the outlet is below the inlet.

What you need:

• Clear flexible tubing, 1-2 cm inner diameter, at least 2 meters long (auto parts stores, hardware stores, aquarium supply)
• A container lower than the fuel tank (5-gallon jerry can, bucket, any vessel)

Method:

1. Open the fuel filler cap.
2. Feed the hose into the tank until you feel it hit bottom. Pull back 2-3 cm so the end is not sealed against the tank floor.
3. Place your collection container on the ground (below the tank).
4. Starting the flow — mouth method (last resort): Suck on the free end of the hose until fuel approaches your mouth, then quickly lower it into the container. Swallowing gasoline causes nausea and chemical burns to the esophagus. This method works but is dangerous.
5. Starting the flow — jiggle method (preferred): Rapidly push the hose in and out of the tank by 15-20 cm while keeping the free end below the tank level. The jiggling motion bounces fuel up the tube until gravity takes over. Takes 10-30 seconds of vigorous jiggling.
6. Starting the flow — submersion method: If you have extra hose length, fill the hose with water, plug both ends with your thumbs, insert one end in the tank and release both ends simultaneously. The water drains out and fuel follows.
7. Once flow starts, it continues until the tank is empty or you raise the outlet above the inlet.

Stopping flow: Raise the outlet end above the fuel level in the tank, or pinch the hose.

Pump Siphon & Transfer Pumps

Hand siphon pumps — a squeeze bulb in the middle of a hose. Squeeze repeatedly to start flow, then gravity takes over. Available at auto parts stores, marine supply, hardware stores. This is the safest and easiest method. If you find one, take it.

Rotary hand pumps — a crank-operated pump that threads into fuel drums or tank openings. More flow than a siphon. Farm supply stores, industrial suppliers. These are excellent for gas station underground tanks.

Battery-powered transfer pumps — 12V pumps designed for fuel transfer. Auto parts stores. They move fuel faster than siphoning and work regardless of relative height. Powered from any 12V battery.

Bypassing Anti-Siphon Devices

Vehicles manufactured after roughly 2005 (varies by manufacturer) have anti-siphon screens, flapper valves, or narrow-diameter filler necks that prevent inserting a standard hose.

Workaround 1: Smaller tubing. Use 6-8 mm (1/4 inch) tubing. This fits through most anti-siphon flaps. Flow is slower but works.

Workaround 2: Access the fuel line. Crawl under the vehicle. The fuel line runs from the tank to the engine along the frame rail. It is a rubber or nylon hose (or metal tube with rubber connectors). Cut the rubber section and drain into a container below. Caution: fuel under residual pressure may spray. Wear eye protection.

Workaround 3: Puncture the tank. As a last resort, drill or punch the tank bottom. Fuel tanks are plastic on most modern cars and can be punctured with a drill, awl, or sharp spike. Position your container below the hole. This is wasteful (you cannot stop the flow easily) and creates an ignition hazard with steel-tanked vehicles (sparks + fuel vapor).

Workaround 4: Use the fuel pump. If the vehicle’s battery still works: locate the fuel pump relay (fuse box, usually under the hood or dashboard). Remove the relay. Connect a jumper wire where the relay was to energize the pump. Disconnect the fuel line at the engine and route it into your container. The pump pushes fuel at 2-4 liters per minute. This is the cleanest method for modern vehicles.

Fuel Types & Properties

Gasoline

Composition: A blend of hydrocarbons refined from petroleum, with additives including detergents, anti-knock compounds (octane boosters), and (in most countries) 10% ethanol.

Shelf life:

• Pure gasoline (no ethanol): 6-12 months in a sealed container in moderate temperatures. Can last longer in ideal conditions.
• E10 (10% ethanol): 3-6 months. Ethanol absorbs water from the atmosphere (“phase separation”), creating a water-ethanol layer at the bottom that does not burn properly and corrodes fuel systems.
• With stabilizer (Sta-Bil, PRI-G): 12-24 months for E10, up to 36 months for pure gasoline.

Signs of degradation:

• Color changes from clear/light amber to dark amber or brown
• Sour or varnish-like smell (fresh gasoline smells sharp and hydrocarbon-sweet)
• Visible layers or sediment in the container
• Gummy or varnish-like residue on container walls

Degraded gasoline is not useless. It burns — just poorly. Mix degraded gas 50/50 with fresh gas. It will run in most engines, though with reduced power and potential carburetor/injector fouling. In a survival context, imperfect combustion beats no combustion.

Diesel & Heating Oil

Shelf life: 6-12 months without treatment, 12-24 months with biocide/stabilizer.

Primary degradation mechanism: Microbial growth. Bacteria and fungi (“diesel bug” or “algae”) grow at the water-fuel interface in diesel tanks. They produce sludge that clogs filters and injectors. This is the main reason diesel goes bad.

Prevention:

• Keep tanks full to minimize condensation (water) space
• Add biocide (Biobor JF is the standard) per label instructions
• Filter through a 10-micron fuel filter before use
• Water separators (available at auto parts stores) remove water from diesel

Cold weather issue: Diesel contains paraffin wax that gels (solidifies) at low temperatures. “Winter diesel” is treated to resist gelling. If you have only summer diesel and temperatures will drop below -10°C, add 10-20% kerosene or gasoline to prevent gelling. This is a standard emergency practice.

Propane, Kerosene & Other Fuels

Propane (LPG):

• Shelf life: indefinite in a sealed, undamaged tank
• Stored as liquid under pressure, vaporizes when released
• Burns very cleanly with minimal residue
• Tanks are refillable if you find a bulk propane tank with liquid remaining
• Safety: heavier than air. Leaking propane pools at floor level. Never use or store propane in enclosed below-grade spaces (basements)

Kerosene (paraffin / #1 fuel oil):

• Shelf life: 2-5 years in a sealed container
• Burns in lamps, heaters, jet fuel is kerosene, some stoves
• Less volatile than gasoline — safer to handle and store
• Will work in diesel engines as an emergency fuel (lower lubricity; add 1% motor oil)

Natural gas: Pipelines stop without compressor stations. Any natural gas in lines dissipates within days. Not a viable post-collapse fuel unless you are near a wellhead.

Storage & Safety

Approved vs. Improvised Containers

Approved fuel containers:

• Jerry cans (NATO-style) — 20 liters, metal, sealed pour spout, ventilated. The gold standard. Find at military surplus, hardware stores, off-road shops.
• Plastic gas cans — 5-20 liters, HDPE plastic, self-venting. Available everywhere. Adequate for short-term storage. Gasoline vapors slowly permeate thin plastic over months.
• Metal drums — 55-gallon (208 liter) steel drums. Excellent for bulk storage. Must have sealed bungs.
• IBC totes — 275-330 gallon (1,000-1,250 liter) plastic cubes in metal cage. Farm supply, industrial sites. Originally for chemicals, but cleaned ones work for fuel.

What NOT to store fuel in:

• Thin plastic (milk jugs, water bottles, trash bags) — gasoline dissolves some plastics and permeates others
• Glass — does not react with fuel but shatters. Acceptable only for small quantities in a protected location
• Anything that previously held food or water and is not thoroughly dry — water in gasoline causes phase separation and corrosion
• Unsealed containers — evaporation loses your volatile fractions (the parts that ignite easily)

Fuel Stabilization & Treatment

Commercial stabilizers: Sta-Bil, PRI-G (gasoline), PRI-D (diesel). Found at auto parts stores, marine supply, hardware stores. Follow the dosage on the label — more is not better.

What stabilizers actually do: They contain antioxidants that slow the chemical chain reactions that break down fuel molecules into gums and varnishes. They do not reverse degradation. Add stabilizer to fresh fuel, not to fuel that has already gone bad.

Improvised stabilization: There is no true substitute for commercial stabilizers. The best improvised approach is:

1. Start with the freshest fuel available
2. Fill containers completely (minimal air space)
3. Seal tightly
4. Store in a cool, dark location (temperature swings accelerate degradation)
5. Use the oldest fuel first (FIFO — first in, first out)

Fire & Vapor Safety

Gasoline vapor, not liquid gasoline, is what explodes. A cup of liquid gasoline in open air burns energetically but controllably. A cup of gasoline in an enclosed space produces enough vapor to fill the space and create an explosive fuel-air mixture that detonates.

Critical safety rules:

• Never siphon, pour, or store gasoline near open flame, sparks, or hot surfaces. This includes cigarettes, campfires, running engines, and electric switches that arc.
• Work outdoors or in well-ventilated spaces. Gasoline vapor is heavier than air and pools in low areas, enclosed spaces, and depressions in the ground.
• Ground yourself before handling fuel. Touch a metal part of the vehicle before opening the fuel cap. Static discharge ignites fuel vapor. This is not theoretical — it happens.
• Do not siphon in direct sunlight on hot days if possible. Heat increases vapor pressure and evaporation rate.
• Have a fire extinguisher or dirt/sand nearby. Water does not extinguish gasoline fires effectively — it spreads the burning fuel. Smother with dirt, sand, or a fire extinguisher rated for Class B (flammable liquids).
• Spill management: If you spill fuel, do not ignite anything nearby until the spill has evaporated completely (15-30 minutes in warm weather, longer in cold). Mark the spill area.

Gasoline on Skin

Gasoline degreases skin and is absorbed through it. Prolonged contact causes chemical burns and systemic toxicity. If you get gasoline on your skin, wash immediately with soap and water. If you swallow gasoline during mouth-siphoning: do NOT induce vomiting (aspiration of gasoline into the lungs is worse than stomach exposure). Drink water to dilute. Seek medical attention if available.

The From-Scratch Perspective

If modern fuel is unavailable or exhausted, your options narrow to:

• Wood gas (syngas): A gasifier converts wood, charcoal, or biomass into a combustible gas that can run internal combustion engines. Complex to build but well-documented. See Vehicle & Machinery Cannibalization for engine conversion.
• Ethanol distillation: Ferment sugar-rich crops (corn, sugar beets, potatoes, fruit), then distill. Requires a still, heat source, and feedstock. The output runs modified gasoline engines and serves as lamp fuel, solvent, and antiseptic.
• Biodiesel: Used cooking oil + methanol + lye catalyst → biodiesel. Works in any diesel engine without modification.
• Rendered animal fat and plant oils: Work directly in oil lamps, some diesel engines (with modifications), and as lubricants.
• Charcoal: The most accessible fuel to produce from scratch. Any hardwood, heated in a low-oxygen environment, becomes charcoal. Higher energy density than raw wood, burns cleaner, and stores indefinitely.

The key insight: salvaged modern fuel buys you time to establish these renewable fuel cycles. Every liter of gasoline you save now is time you would otherwise spend producing fuel from scratch.