As an Amazon Associate and eBay Partner, toptenpick.com earns from qualifying purchases. Prices and availability are subject to change.
GY6 engines run a wet clutch inside a CVT case, so they need motorcycle-spec JASO MA or MA2 oil — automotive “energy conserving” oil will make the clutch slip. Most riders run 10W-40 (15W-40 or 5W-40 also show up depending on climate). Note that the GY6’s separate rear transmission/gearbox typically needs its own 80W-90 gear oil — that’s a different product from everything below, which covers the engine only.
| # | Product | Price | Where to buy |
|---|---|---|---|
| 1 | Motul 5100 10W-40 4T | $18-$21/qt | Amazon |
| 2 | AMSOIL Formula 4-Stroke Synthetic Scooter Oil | $12-$17/qt | Amazon · eBay |
| 3 | Bel-Ray EXS Full Synthetic Ester 10W-40 | $18-$22/L | Amazon · eBay |
| 4 | Maxima Pro Plus 10W-40 Synthetic | $15-$18/L | Amazon · eBay |
| 5 | Valvoline 4-Stroke Motorcycle Full Synthetic 10W-40 | $13-$16/qt | Amazon · eBay |
| 6 | Mobil 1 Racing 4T 10W-40 | $12-$14/qt | Amazon · eBay |
| 7 | Castrol Power1 4T 10W-40 Full Synthetic | $8-$9/qt | Amazon · eBay |
| 8 | Lucas Oil High Performance Synthetic 4T 10W-40 with Moly | $13-$16/qt | Amazon · eBay |
| 9 | Yamalube Performance All Purpose 4-Stroke 10W-40 | $11-$14/qt | Amazon · eBay |
| 10 | Royal Purple Max-Cycle 10W-40 | $15-$18/qt | Amazon · eBay |
The picks, in detail
Motul 5100 10W-40 4T
Explicitly marketed by Motul for 50cc-150cc GY6 scooters, ATVs and go-karts — the single most directly-targeted product on this list.
- Technosynthese ester blend
- JASO MA2 certified, wet-clutch safe
- Marketed specifically for GY6-class engines
- Purpose-marketed for exactly this engine family
- Smooth clutch engagement
- Pricier than conventional 10W-40 options
AMSOIL Formula 4-Stroke Synthetic Scooter Oil
AMSOIL’s dedicated scooter-line synthetic, formulated for air-cooled small-displacement 4-stroke engines like the GY6.
- 100% synthetic, scooter-specific formulation
- JASO MA2 rated
- 10W-40 viscosity
- Purpose-built for small-displacement scooter engines
- Strong synthetic base stock
- Sold mainly through AMSOIL dealers rather than big-box retailers
Bel-Ray EXS Full Synthetic Ester 10W-40
An ester-based full synthetic sold through powersports retailers, commonly run in GY6-based scooters for its high-temperature stability.
- Ester-based full synthetic
- JASO MA2 rated
- Sold in 1L and 4L sizes
- High-quality ester base stock
- Good heat stability for CVT-adjacent engine bays
- Sold by the liter, not the U.S. quart
Maxima Pro Plus 10W-40 Synthetic
A racing-oil-brand synthetic exceeding JASO MA2 that’s common across small-displacement 4-strokes including scooters.
- Synthetic blend exceeding JASO MA2
- 10W-40 viscosity
- 1L and gallon sizes
- Strong racing-oil pedigree
- Good availability at powersports shops
- Gallon size is a bigger upfront spend for a small engine
Valvoline 4-Stroke Motorcycle Full Synthetic 10W-40
A mainstream, easy-to-find full synthetic that meets JASO MA2 — useful when you want a reliable option from a local auto parts store rather than a powersports specialist.
- Full synthetic
- JASO MA2 rated
- 10W-40 viscosity
- Widely available at Walmart/AutoZone
- Sold in convenient single-quart or multi-packs
- Less of a scooter-specific marketing focus than Motul/AMSOIL
Mobil 1 Racing 4T 10W-40
The motorcycle-specific Mobil 1 line (not the automotive product), frequently recommended in GY6 forums for its clutch-safe formulation.
- Full synthetic, JASO MA2 rated
- 10W-40 viscosity
- Wet-clutch safe formulation
- Widely available at auto parts stores
- Strong reputation across small-engine communities
- Don’t confuse with automotive Mobil 1 — different formulation
Castrol Power1 4T 10W-40 Full Synthetic
One of the cheapest full synthetics that still meets JASO MA2, making it a budget-friendly synthetic upgrade over conventional oil.
- Full synthetic
- JASO MA2 rated
- 10W-40 viscosity
- Lowest-priced full synthetic in this list
- Sold in convenient multi-packs
- Less scooter-specific reputation than Motul/AMSOIL
Lucas Oil High Performance Synthetic 4T 10W-40 with Moly
A moly-additized synthetic aimed at added wear protection, sold through most powersports parts retailers.
- Synthetic with moly additive package
- JASO-rated wet-clutch safe
- 10W-40 viscosity
- Extra wear-protection additives
- Competitive pricing
- Less scooter-specific brand recognition
Yamalube Performance All Purpose 4-Stroke 10W-40
A budget mineral-base oil that still meets JASO MA2 — oil brand doesn’t need to match the engine brand, only the spec does.
- JASO MA2 rated
- 10W-40 viscosity
- Mineral-base formulation
- One of the most budget-friendly options here
- Meets the same wet-clutch safety spec as pricier oils
- Mineral base rather than synthetic
Royal Purple Max-Cycle 10W-40
A premium synthetic marketed for motorcycle and small-engine wet clutches, sold in quarts or case packs.
- High-performance synthetic
- JASO MA2 rated
- 10W-40 viscosity
- Premium additive package
- Well-regarded across small-engine forums
- One of the pricier options here
Buying tips
- Avoid automotive “energy conserving” oil — the friction modifiers cause wet-clutch slip in GY6-based scooters just like on full-size motorcycles.
- GY6 scooters have a separate CVT/rear transmission gearbox that takes its own 80W-90 (or manufacturer-specified) gear oil — don’t put engine oil in that case, and don’t put gear oil in the engine.
- 10W-40 covers most climates; consider 5W-40 for cold starts or 15W-40 in sustained hot weather.
- Small GY6 sumps (often under a quart) mean the price-per-oil-change gap between budget and premium oils is smaller in dollars than it looks per-quart — synthetic is affordable here even at the premium end.
As an Amazon Associate and eBay Partner, toptenpick.com earns from qualifying purchases. Prices and availability are subject to change.