Cost & budgeting
Avgas vs UL91 vs Mogas: Real UK Fuel Costs
We compared live prices across UK airfields to show what avgas, UL91 and mogas actually cost per hour for a PA-28 and a C152.
Across the Airfield Atlas directory, published 100LL Avgas prices range from £1.73 per litre at Old Sarum (EGLS) and £1.96 per litre at Netherthorpe (EGNF) up to £2.45 per litre at Caernarfon (EGCK) and Fife (EGPJ). Over the same network, UL91 sells between £2.10 per litre at Perth/Scone (EGPT) and £2.60 per litre at Shobdon (EGBS).
For a Piper PA-28-161 burning 33.3 litres per hour, uplift location creates a direct operating variance of £24.00 per flying hour on 100LL alone. When you factor in engine tolerances, supplemental type certificates, and spark plug maintenance, fuel grade selection becomes an essential operational decision.
Sourced UK airfield pump prices
Fuel prices across the UK network reflect individual aerodrome contracts and tax treatments. Some aerodromes publish gross prices inclusive of 20% VAT, while others quote net commercial rates before tax.
| Airfield Name | ICAO | Fuel Grade | Published Price | Basis | Gross Equivalent (Inc 20% VAT) |
|---|---|---|---|---|---|
| Old Sarum | EGLS | Avgas 100LL | £1.73 / L | Inc VAT | £1.73 / L |
| Netherthorpe | EGNF | Avgas 100LL | £1.96 / L | Inc VAT | £1.96 / L |
| Perth / Scone | EGPT | Avgas 100LL | £1.90 / L | Inc VAT | £1.90 / L |
| Sherburn-in-Elmet | EGCJ | Avgas 100LL | £2.08 / L | Inc VAT | £2.08 / L |
| Oaksey Park | EGTW | Avgas 100LL | £2.05 / L | Inc VAT | £2.05 / L |
| Sywell | EGBK | Avgas 100LL | £2.15 / L | Inc VAT | £2.15 / L |
| Leicester | EGBG | Avgas 100LL | £2.15 / L | Inc VAT | £2.15 / L |
| Compton Abbas | EGHA | Avgas 100LL | £2.25 / L | Inc VAT | £2.25 / L |
| Shobdon | EGBS | Avgas 100LL | £2.28 / L | Inc VAT | £2.28 / L |
| Turweston | EGBT | Avgas 100LL | £2.29 / L | Inc VAT | £2.29 / L |
| Wolverhampton Halfpenny Green | EGBO | Avgas 100LL | £2.34 / L | Inc VAT | £2.34 / L |
| Caernarfon | EGCK | Avgas 100LL | £2.45 / L | Inc VAT | £2.45 / L |
| Fife | EGPJ | Avgas 100LL | £2.45 / L | Inc VAT | £2.45 / L |
| Perth / Scone | EGPT | UL91 | £2.10 / L | Inc VAT | £2.10 / L |
| Sherburn-in-Elmet | EGCJ | UL91 | £2.24 / L | Inc VAT | £2.24 / L |
| Compton Abbas | EGHA | UL91 | £2.32 / L | Inc VAT | £2.32 / L |
| Shobdon | EGBS | UL91 | £2.60 / L | Inc VAT | £2.60 / L |
Notice that UL91 is not universally cheaper than 100LL at every pump. At Compton Abbas, 100LL is £2.25/L while UL91 is £2.32/L. At Shobdon, 100LL is £2.28/L while UL91 is £2.60/L. Because UL91 is delivered in smaller batch volumes to specialized tanks, transport overheads can push its retail price higher than high-turnover 100LL.
Engine compatibility and fuel specifications
Avgas 100LL
Avgas 100LL remains the default certified fuel for piston aircraft across Britain. Formulated to Def Stan 91-090, it contains tetraethyl lead (TEL) to prevent detonation in high-compression engines like the Lycoming IO-360 and Continental IO-390. That lead lubricates valve guides, but also leads to spark plug fouling during low-power ground idling and requires 50-hour oil and filter changes.
UL91
UL91 is an unleaded aviation gasoline conforming to ASTM D7547. It contains zero lead and zero ethanol, completely preventing plug fouling and lead contamination in oil sumps. It is certified for low-compression engines including the Continental O-200 and O-235, as well as Rotax 912 and 914 series powerplants. It cannot be used in high-compression or turbocharged engines requiring 100-octane detonation protection.
Mogas (BS EN 228 Super Unleaded)
Mogas refers to automotive pump gasoline. Under UK CAA Safety Sense Leaflets and Light Aircraft Association (LAA) Technical Leaflets, only high-octane Super Unleaded (97 to 99 RON, labelled E5 with maximum 5% ethanol) is permitted under specific airframe and engine Supplemental Type Certificates (STCs). Standard forecourt E10 petrol is strictly prohibited due to fuel bladder degradation, carb seal failure, and high vapor lock risk.
Per-hour fuel cost by aircraft preset
Burn rates below are the POH-sourced figures already used in the Airfield Atlas trip cost calculator. For the pump prices, we've used Sywell's £2.15/L for Avgas and Sherburn-in-Elmet's £2.24/L for UL91 — both real, current directory prices, not a statistical average — as a fixed reference so the hourly figures below are comparable across aircraft. Mogas isn't in the directory yet: we have no verified UK airfield mogas price on file, so the £1.45/L used below is a general UK forecourt Super Unleaded estimate, not Airfield Atlas data. Treat the Mogas column as illustrative until we have real pump prices to show.
Cessna 152
- Preset Burn Rate: 23.1 litres / hour (104 kts cruise)
- Avgas 100LL (@ £2.15/L): £49.67 / hour
- UL91 (@ £2.24/L): £51.74 / hour
- Mogas (@ £1.45/L with STC): £33.50 / hour
- 100-Hour Annual Difference (100LL vs Mogas): £1,617 annual savings.
The Continental O-235 engine runs exceptionally clean on unleaded fuels. Burning Mogas eliminates lead ring deposits and reduces unscheduled plug clearing intervals.
Piper PA-28-161 Warrior II
- Preset Burn Rate: 33.3 litres / hour (110 kts cruise)
- Avgas 100LL (@ £2.15/L): £71.60 / hour
- UL91 (@ £2.24/L): £74.59 / hour
- Mogas (@ £1.45/L with STC): £48.29 / hour
- 100-Hour Annual Difference (100LL vs Mogas): £2,331 annual savings.
The Lycoming O-320-D3G is approved for Mogas under approved LAA or Petersen STCs, provided each fuel batch passes an on-site water-shake ethanol test.
Cessna 172 Skyhawk
- Preset Burn Rate: 28.0 litres / hour (115 kts cruise)
- Avgas 100LL (@ £2.15/L): £60.20 / hour
- UL91 (@ £2.24/L): £62.72 / hour (Where engine compression permits)
- 100-Hour Annual Difference (100LL vs UL91): UL91 carries a slight £252 premium at median UK pump rates.
Tecnam P2008 (Rotax 912)
- Preset Burn Rate: 17.0 litres / hour (116 kts cruise)
- UL91 (@ £2.24/L): £38.08 / hour
- Mogas (@ £1.45/L): £24.65 / hour
- 100-Hour Annual Difference (UL91 vs Mogas): £1,343 annual savings.
Rotax 912 engines are designed primarily for unleaded automotive fuel. Running a Rotax on leaded 100LL is permitted but requires halving the oil change interval to 50 hours to prevent gearbox sludge buildup.
| Aircraft Preset | Fuel Burn (POH) | Cruise Speed | Avgas Hourly (@ £2.15) | UL91 Hourly (@ £2.24) | Mogas Hourly (@ £1.45) |
|---|---|---|---|---|---|
| Ikarus C42 | 12.0 L/h | 90 kts | N/A | £26.88 | £17.40 |
| Tecnam P2008 | 17.0 L/h | 116 kts | £36.55 | £38.08 | £24.65 |
| Cessna 152 | 23.1 L/h | 104 kts | £49.67 | £51.74 | £33.50 |
| Van's RV-7/RV-9 | 27.0 L/h | 150 kts | £58.05 | N/A | £39.15 |
| Robin DR400/160 | 27.0 L/h | 118 kts | £58.05 | N/A | £39.15 |
| Cessna 172 | 28.0 L/h | 115 kts | £60.20 | £62.72 | £40.60 |
| PA-28-161 Warrior | 33.3 L/h | 110 kts | £71.60 | £74.59 | £48.29 |
| Cirrus SR20 | 34.8 L/h | 144 kts | £74.82 | N/A | N/A |
| PA-28-181 Archer | 36.0 L/h | 122 kts | £77.40 | N/A | £52.20 |
| Cirrus SR22 | 47.0 L/h | 166 kts | £101.05 | N/A | N/A |
Airfield selection vs fuel grade selection
Airfield location frequently creates a larger financial delta than switching fuel grades.
Consider uplifting 100 litres of 100LL:
- Uplifting at Netherthorpe (EGNF) @ £1.96/L = £196.00
- Uplifting at Caernarfon (EGCK) @ £2.45/L = £245.00
- Direct Airfield Difference: £49.00 on the same 100-litre fill.
Choosing your refuelling airfield with care saves more money than changing between 100LL and UL91 at the same field.
| Airfield | Avgas price | PA-28-161 hourly cost (33.3 L/hr) |
|---|---|---|
| Netherthorpe (EGNF) | £1.96 / L | £65.27 |
| Sywell (EGBK) | £2.15 / L | £71.60 |
| Turweston (EGBT) | £2.29 / L | £76.26 |
| Caernarfon (EGCK) | £2.45 / L | £81.59 |
Same engine, same burn rate, £16.32 per flight hour of spread — purely from where you chose to fill up.
Practical Mogas testing protocol for UK operators
If your aircraft holds an STC for automotive fuel and you uplift Super Unleaded (E5) from local garages:
- Verify the Ethanol Content: Use a standard graduated fuel tester. Add 50ml of fuel and 10ml of water, shake for 30 seconds, and allow to settle. If the water boundary expands above 10ml, the fuel has absorbed ethanol and must not be used in non-ethanol-rated tanks.
- Account for Vapor Pressure in Warm Weather: Automotive fuel has higher Reid Vapor Pressure (RVP) than aviation fuel. Avoid high-altitude climbs on hot summer days with warm automotive fuel to prevent vapor lock in gravity-fed lines.
- Check Airfield Rules on Jerry Cans: Many licensed aerodromes prohibit refuelling from plastic containers on the active apron due to static grounding rules and aerodrome fire licenses.
Check the Airfield Atlas directory for verified fuel availability, published prices, and VAT terms before planning cross-country fuel stops.