Costco Gas Prices in San Marcos, CA
- Regular avg
- $5.299▲ +$0.040
- Premium avg
- $5.759▲ +$0.030
- Stations reporting
- 2
Avg of 2 stations · per gallon · ▲▼ change since the previous day
Price history in San Marcos
Last 30 days · per gallonRegular: $5.859 on Oct 15 to $5.299 on Nov 13, low $5.259, high $5.859. Premium: $6.259 on Oct 15 to $5.759 on Nov 13, low $5.729, high $6.259.
Costco gas in San Marcos today
San Marcos has 2 Costco gas stations: San Marcos at 725 Center Drive and San Marcos Business Centre at 150 S. Bent Ave.
Both stations post the same Regular price today, $5.299.
Costco Regular prices in San Marcos have eased about $0.560 over the past month, from $5.859 a month ago.
The furthest any single station moved was San Marcos, down $0.560.
- vs the California average
- $0.280 above, at $5.019
- Diesel
- sold at none of the 2 stations
Costco gas stations in San Marcos
Fuel grades at Costco in San Marcos
All 2 Costco gas stations in San Marcos sell Kirkland Signature fuel, which is Top Tier certified. None of them reported a diesel price in the last 30 days.
| Grade | Stations | Avg today | Cheapest |
|---|---|---|---|
| Regular | 2 | $5.299 | San Marcos $5.299 |
| Premium | 2 | $5.759 | San Marcos $5.759 |
Regular
all 2 stations87-octane Kirkland Signature unleaded, the grade most cars are built for.
- Same TOP TIER detergent package as premium. The only difference between the two is octane.
- Can contain up to 10% ethanol, like most US gasoline. The pump label shows the blend.
Premium
all 2 stationsKirkland Signature premium: 91 octane at most stations, 93 in some regions.
- Only needed if your owner’s manual requires or recommends premium. Higher octane resists engine knock; it adds nothing to an engine built for regular.
- Carries the same detergent additives as regular.
Not sold at Costco
- Mid-grade (89): Costco pumps offer regular and premium only.
- Cash sales: every Costco pump is card-only.
Is Costco gas in San Marcos good quality?
Costco does not sell a refiner’s brand. Every pump in San Marcos dispenses Costco’s own Kirkland Signature fuel, bought from major refiners and distributors in the region and finished with Costco’s additive package.
Kirkland Signature gasoline is licensed TOP TIER, the detergent standard set by automakers including GM, Ford, Toyota, Honda and BMW. Costco puts its detergent level at about five times the EPA minimum, which is what keeps intake valves and fuel injectors clear of carbon deposits. Costco’s gasoline also contains friction modifiers that it says reduce engine wear.
In short, the low price is not a lower grade. The saving comes from Costco running its gas as a membership perk on thin margins, not from the fuel.
Costco gas station hours in San Marcos
On weekdays the earliest pumps in San Marcos come on at 5:30 a.m. (San Marcos) and the last ones switch off at 10 p.m. (San Marcos). Pump hours run longer than the warehouse's, and weekends are shorter. Times are local.
| Station | Mon–Fri | Sat | Sun |
|---|---|---|---|
| San Marcos | 5:30 a.m. – 10 p.m. | 6 a.m. – 8:30 p.m. | 6 a.m. – 7:30 p.m. |
| San Marcos Business Centre | 6 a.m. – 10 p.m. | 6 a.m. – 8:30 p.m. | 6 a.m. – 7:30 p.m. |
What else is at Costco warehouses in San Marcos
Every Costco gas station sits in a warehouse parking lot, so a fill-up can share a trip with the rest of the list.
- Food court
- 1 of 2
- Pharmacy
- 1 of 2
- Optical
- 1 of 2
- Tire center
- 1 of 2
- Car wash
- 0 of 2
- EV charging
- 0 of 2
How Costco gas works in San Marcos
Bring your card. The pump asks for an active Costco membership card before it starts, at all 2 gas stations in San Marcos. Without a membership, a Costco Shop Card loaded with credit works the same way.
Pay by card. The pumps take Visa, most debit cards and the Costco Shop Card. There is no cash, and a card hold of up to $150 can show until the fill posts.
Check the price first. Each station sets its own price, usually once a day, so two Costco stations in San Marcos can differ. Today the regular average here is $5.299. The prices on this page are collected once daily and can lag a same-day change at the pump.
Go early or late. Lines are longest on weekend afternoons and weekday evenings. The first pumps here open at 5:30 a.m. on weekdays.
Cities near San Marcos
- Costco gas prices Vista · CA · 8 mi$5.259
- Costco gas prices Carlsbad · CA · 9 mi$5.259
- Costco gas prices Poway · CA · 16 mi$5.259
- Costco gas prices San Diego · CA · 21 mi$5.229
- Costco gas prices Santee · CA · 23 mi$5.199
- Costco gas prices La Mesa · CA · 26 mi$5.159
- Costco gas prices Temecula · CA · 27 mi$4.999
- Costco gas prices Murrieta · CA · 32 mi$4.999
States near California
- Costco gas prices Nevada · 9 stations$4.379
- Costco gas prices Arizona · 21 stations$3.658
- Costco gas prices Utah · 16 stations$3.833
- Costco gas prices Idaho · 8 stations$3.824
Costco gas in San Marcos: common questions
Where is the cheapest Costco gas in San Marcos today?
Nowhere in particular — both Costco gas stations in San Marcos post the same Regular price, $5.299, as of the November 13, 2026 reading.
How many Costco gas stations are there in San Marcos?
San Marcos has 2 Costco warehouses with a gas station, and both of them reported a price in the last 30 days.
Does any Costco gas station in San Marcos sell diesel?
No — none of the 2 stations in San Marcos has reported a diesel price in the last 30 days. Costco sells diesel at a minority of its locations in the US.
Is Costco gas cheaper in San Marcos than in California?
No — the average Costco Regular price in San Marcos is $5.299, $0.280 above the California average of $5.019 as of the November 13, 2026 reading.
Are Costco gas prices in San Marcos going up or down?
Down — the average Costco Regular price in San Marcos has eased about $0.560 over the past month, from $5.859 to $5.299.