SA Fuel Prices – Week of 18 May 2026

South Australia is the cheapest state in the country for petrol right now, with metro U91 sitting at 176.8 c/L — well below the national metro average of 183.8 c/L. That's a 7c advantage over the rest of Australia, and it's the second consecutive week prices have eased.

SA Petrol Prices Snapshot: 18–25 May 2026

SA Diesel Fuel Prices Fall Sharply This Week

The standout story is diesel. Metro diesel dropped 4.8c to 224.4 c/L, while rural diesel fell an even more significant 8.5c to 236.7 c/L. For tradies and anyone who covers long country distances, that rural drop is genuinely meaningful over a full tank.

The daily data shows a clean, consistent slide all week. Metro diesel opened Monday at 225.7 c/L and eased steadily to 223.1 c/L by Saturday before nudging fractionally back to 223.2 c/L on Sunday. No spikes, no reversals — just a steady drift down.

U91 metro told a slightly different story. It dipped to 175.1 c/L on Monday before creeping back up mid-week to 177.3 c/L on Thursday, then hovering in the 177.0–177.2 c/L range through the weekend. The weekly average of 176.8 c/L reflects that modest bounce, but the two-week downward trend is still intact. Current prices are also sitting close to the 30-day metro low of 166.7 c/L, suggesting the market hasn't completely given back the relief drivers enjoyed recently.

P95 metro eased slightly to 193.2 c/L, though rural P95 bucked the trend with a small 1.4c rise to 211.5 c/L.

How Much You Can Save Shopping Around for Petrol in SA

The gap between the cheapest and priciest metro stations this week is a remarkable 33.2c per litre. Costco Kilburn came in at 166.7 c/L for U91, while the most expensive metro station reached 199.9 c/L. On a 50-litre fill, that difference is over $16.

Brand averages reinforce how much the choice of station matters. Liberty averaged 169.7 c/L, United 170.8 c/L, and Mobil 170.9 c/L for metro U91. BP averaged 182.1 c/L and EG Ampol 181.9 c/L. That's more than a 12c gap between the cheapest and priciest branded averages, purely based on where you pull in.

Last Week's Cheapest Fill-Up Day

Last Monday, 18 May, was the cheapest day to fill up in SA metro, with U91 hitting 175.1 c/L. If you timed it right, you paid notably less than the weekly average.

It's also worth mentioning that supply conditions improved this week. The number of stations flagged as out-of-stock across SA fell from 139 to 112 station-fuels. P95 saw the sharpest improvement, dropping from 12 out-of-stock to just 4, and U91 improved from 32 to 25. If you've been striking dry pumps lately, things are looking a bit more reliable now.

SA Metro Petrol Price Forecast: 25–27 May 2026

The short-term outlook suggests metro U91 will edge upward from the current 176.8 c/L. The forecast has prices at 178.3 c/L on Sunday (78% confidence), climbing to 179.1 c/L on Monday and 179.6 c/L by Tuesday. That's a potential rise of around 2.8c over three days, though confidence softens as the window extends.

Make the Most of SA's Cheap Fuel Right Now

SA drivers are in a genuinely good position compared to the rest of the country. If you need to fill up, sooner is better given the forecast. Sticking to lower-cost brands and using a price comparison tool can stretch that advantage even further. With a 33c spread across metro stations, the effort is absolutely worth it.

Petrol Smart shows you live prices on the map so you can see exactly which stations near you are cheapest before you leave home. Download it for free, no ads, no fuss — just smarter fills every time.