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Generator School · 03

Diesel vs petrol — storage, life, safety

Almost every customer who asks us 'should I get diesel or petrol?' gets the same answer: it depends on the duty. For occasional camp / weekend use under 8 kVA, petrol is cheaper to buy and lighter to move. For anything that has to start reliably after sitting unused — backup, standby, prime-power — diesel wins, almost always.

01

Fuel storage life

Pump petrol starts to oxidise within 30 days, especially with ethanol blends (E10). After 3 months unused, it varnishes carburettors and fouls fuel lines. Diesel, with a fuel stabiliser, keeps for 12+ months without trouble. For backup duty, this alone is decisive — your generator is most needed when it hasn't been started for months.
02

Service life and overhaul intervals

A well-maintained petrol generator typically reaches 1500–3000 hours before needing a top-end rebuild. A diesel — even a small Yanmar L-series — comfortably hits 10,000+ hours before overhaul. For a unit running 2 hours a week, that's the difference between 15 years and 100 years of service life.
03

Fire and safety

Petrol flashes at -43 °C — it's volatile, easy to ignite, and regulated under stricter dangerous-goods rules for transport and storage. Diesel flashes at >52 °C — it won't ignite from a match or cigarette dropped into it. For workplace and home storage, diesel is dramatically safer.
04

Where petrol still wins

Portable inverter units under 4 kVA where weight and price matter most (camping, tradies, light AV). Pramac's P-series petrol inverters are excellent at this duty and produce clean sine-wave output safe for laptops, comms gear, and medical equipment.
Quick answers

FAQs

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Yes, with proper biocide and stabiliser additives, and an annual fuel polish to remove water. Without treatment, microbial growth in 12–24 months will clog filters.

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