EXPLAINED: WHICH MOTOREX TOP SPEED 4T GRADE DOES YOUR BIKE NEED?

MOTOREX’s Top Speed 4T isn’t a single one-size-fits-all synthetic oil – it’s four distinct viscosities, each engineered for a different style of engine and a different set of riding demands. Here’s how to work out which one belongs in your bike.

Ask ten riders what oil they run and you’ll get ten answers – and at least three of those will be “whatever was on special at the time”. But the grade printed on the bottle isn’t marketing waffle. It’s the difference between an oil that holds its film through a 35-degree moto and one that gives up halfway through the second one. MOTOREX splits its Top Speed 4T range across four viscosities, each aimed at a different type of engine and a different set of demands, and Aussie distributor A1 Accessory Imports has put together a rundown on which grade suits what.

For over a century, MOTOREX has been obsessively devoted to producing premium, motorcycle specific oils and lubricants. What started as a small operation has morphed into an undeniable global force in motorsport and now MOTOREX products are trusted to keep multi-million-dollar factory racing programs running at peak performance.

MOTOREX Top Speed 4T isn’t a one-size-fits-all “synthetic” oil. It’s a full range of performance oils, each viscosity engineered for a different style of engine and riding demands, all built on the same Molecular Converted technology with PAO & Ester that keeps the lubrication intact when things get properly hot.

WHAT’S ACTUALLY IN THE BOTTLE?

Every grade in the Top Speed 4T range shares the same core engineering: a specialised blend of premium base oil, PAO and Ester content that clings to metal surfaces, thermal and shear stability that holds viscosity under sustained heat, and low NOACK volatility so less oil burns off in extreme conditions. Every grade also carries JASO MA2 approval, the top rating for shared engine oil systems running wet multi-disc clutches.

FOUR GRADES, FOUR JOBS

TOP SPEED 4T 5W/40

The lightest grade in the range, engineered for faster cold-oil flow to critical components on start-up and reduced internal friction once the engine’s spinning. A strong pick for modern four-strokes where manufacturers spec a lighter grade.

Think: F850 & F900 models, K1600 B, S1000RR, CB1000RR, Brutale 800 + more.

TOP SPEED 4T 10W/30

A lighter option suited to small-to-medium capacity, high-revving engines that call for a thinner film without sacrificing wear protection. A solid, cost-effective step up for smaller-capacity Japanese four-stroke engines.

Think: XL750 Transalp, Africa Twin 1100, CMX1100, NT1100, GB350 + more.

TOP SPEED 4T 10W/40

The versatile all-rounder of the range, and the grade most used across modern Japanese four-stroke motocross and enduro machines in Australia, thanks to its excellent wear protection and stability under sustained heat cycles.

Think: 450MT, 700MT, CB650R, CRF250/450R, Ninja 500/600, KX250/450F, GSX-R1000R, V-Strom 800 & 1000, MT-09, Tenere 700, YZ250/450F + more.

TOP SPEED 4T 15W/50

The heavy hitter, used across both four-stroke engines and transmissions, including European two-stroke transmission applications. Its thicker film makes it the pick for medium-to-large displacement engines, and for anyone riding hard enough that bottom-end bearing protection under sustained heat is non-negotiable.

Think: Desmo 450MX, FTR1200, Super Scout, Himalayan, Interceptor 650, Rocket 3 Storm + more. KTM two-stroke transmission.

SELECTING THE RIGHT MOTOREX OIL FOR YOUR MOTORCYCLE

You don’t need to be chasing world championships for this to matter. You just need to match the oil grade from your manual, then factor in your riding conditions. Whether that’s the light-flowing 5W/40 or the do-it-all 10W/40, MOTOREX Top Speed 4T has a grade engineered for the job at hand.

For the full Top Speed 4T range, head to https://www.motorexoil.com.au/product-category/four-stroke/synthetic-performance/