5W-20 vs 5W-30: Cost Per Quart and Which Your Engine Wants
5W-20 and 5W-30 are priced the same per quart. Across the motor oil we track, 5W-20 runs about $5.19–$6.60 per quart and 5W-30 about $4.59–$11.17, and both sit at a $6.39 median — a rounding error apart. So don't choose on price: use the viscosity your owner's manual specifies. The two numbers differ only in cold-and-hot flow (the "20" vs "30" is thickness at operating temperature), and modern engines are engineered for one of them. The real way to save is buying the 5-quart jug instead of single quarts and sticking to the grade your manual lists.
By OutletPicks Editorial, Independent price-comparison desk 5 min read· updated 7/10/2026profile ↗
What motor oil & fluids costs per quart
Live price terciles across the 48 motor oil & fluids products we track, by real cost per quart.
| Tier | Cost / quart | Example pick |
|---|---|---|
| Budget | $4.27–$6.39 | Valvoline European Vehicle Full Synthetic… ($5.39/quart) |
| Mid-range | $6.39–$8.50 | Valvoline Restore & Protect Full Synthetic… ($7.19/quart) |
| Premium | $8.58–$12.79 | LIQUI MOLY Molygen New Generation 5W-30… ($10.21/quart) |
Walk down the oil aisle and 5W-20 and 5W-30 sit side by side at the same price. That's not a coincidence — the two grades cost essentially the same per quart, so the decision is a spec decision, not a budget one.
The real cost per quart
Across the synthetic motor oil we track on Amazon US:
| Grade | Cheapest / quart | Median / quart | Most expensive / quart | | --- | --- | --- | --- | | 5W-20 | $5.19 | $6.39 | $6.60 | | 5W-30 | $4.59 | $6.39 | $11.17 |
The medians are identical. The spread inside each grade comes entirely from brand and pack size, not from the viscosity number. A large jug of a store-brand synthetic can land near $4.59 per quart; a single quart of a premium brand can run $8–$11. That gap dwarfs any 5W-20-vs-5W-30 difference, which is effectively zero.
So what does the number actually mean?
The "5W" is cold-start flow (how the oil pours when the engine is cold). The second number — 20 or 30 — is how thick the oil stays at full operating temperature. A 30 is slightly thicker when hot than a 20. That's it. Neither is "better." Modern engines are engineered around a target oil-film thickness, and the manufacturer picks the grade that matches it — increasingly 5W-20 on newer engines tuned for fuel economy.
The honest verdict
Because they cost the same, use the grade your owner's manual specifies and spend your attention on the two things that do move the price: buy the biggest jug you'll use before it expires, and buy the cheapest brand that carries the right API/ILSAC certification for your engine.
See every synthetic we track ranked by real cost per quart on the Best motor oil of 2026 page, or browse the full motor oil category.
Top 5 cheapest per quart right now
Live from the catalog, ranked by real cost per quart — cheapest first.
As of July 23, 2026: the cheapest quart we track is ACDelco GM Original Equipment 10-9327 (19432320)… at $4.27/quart. Re-checked daily — the cheapest listings refresh first.
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Frequently asked questions
Is 5W-30 more expensive than 5W-20?
No. Across the synthetic motor oil we track, 5W-20 runs about $5.19–$6.60 per quart and 5W-30 about $4.59–$11.17, and both share a $6.39 per-quart median. Within a single brand's product line the two grades are almost always the same price. Any price gap you see is between brands and pack sizes, not between the two viscosities.
Can I use 5W-30 instead of 5W-20?
Only if your manufacturer approves it. The "20" and "30" describe how thick the oil is at engine operating temperature; modern engines are built with a specific oil-film thickness in mind, and many newer engines are designed around 5W-20 for fuel economy. Using a heavier grade than specified can raise oil pressure and cost you a little efficiency; a lighter one than specified can reduce protection. Follow the owner's manual — it costs the same either way.
What actually saves money on motor oil?
Buy the multi-quart jug, not single quarts, and match the exact grade your manual lists so you're not stuck buying a second bottle. Across our catalog the cheapest synthetic works out to about $4.59 per quart in a large jug versus $8–$11 per quart for single-quart bottles — the pack size, not the viscosity, is where the real spread is.