Kubota GB13 – GB20 Engine Oil and Fluids: All Capacities

Which engine oil should go into a Kubota GB13, GB14, GB15, GB16, GB18 or GB20 — and how much? Below you'll find all fluid capacities and oil types for the complete GB series, taken directly from the original Kubota operator's manuals, translated into oil types you can simply buy today.

Suitable for the entire series: Kubota GB13 (D9/DA5/N), GB14 (B9), GB15 (B9/S), GB16 (K/FK/H), GB18 (K/FK) and GB20 (K/FK).

Kubota GB13, GB14 and GB15: Fluids and Capacities

Kubota GB16, GB18 and GB20: Fluids and Capacities

Kubota GB Engine Oil: Why 15W-40 Is the Right Choice

Kubota originally specified its own D30 (SAE 30) or D10W30. For the D662, D722, D905, D1005 and D1105 engines used across the GB series, a modern mineral 15W-40 diesel engine oil (API SG/CD, SKU-15W40) is the logical successor: the same protection at operating temperature, but with better cold-start properties than the old single-grade SAE 30. If you often start the engine at or below freezing temperatures, the manual explicitly recommends the thinner 10W-30 for winter use — the engine turns over more easily, sparing both the starter motor and the battery.

Change the oil every 100 hours or at least once a year, even with light use: condensation and acidification degrade oil even without running hours. Check the oil level with the tractor on level ground and don't exceed the maximum mark on the dipstick — an oil level that's too high causes black smoke on these engines.

Kubota GB Transmission Oil: One Oil for Gearbox, Hydraulics and Lift

On the GB series, the gearbox, hydraulic system and lift share the same oil reservoir. Kubota specified Super UDT for this; the modern replacement is a GL-4 UTTO transmission/hydraulic oil (SKU-15W402, 10 L). For a GB16K with a 14.8-liter capacity, you'll need to order two bottles. Change every 300 hours and replace the hydraulic filter every 200 hours — fresh oil with a saturated filter is money wasted. The steering housing and front axle also run on the same type of oil; don't forget these two small housings during the 300-hour service.

Slow or sagging lift? Always start with the oil and filter before considering the pump — contaminated oil is by far the most common cause. Read more about this in our blog about the hydraulics and PTO of the GB series.

Coolant and Lubrication Points

Filling the radiator and reserve tank with water plus 50% antifreeze protects down to well below -30°C and — just as importantly — prevents internal corrosion. Replace the coolant every two years and flush the radiator at the same time. Every 50 hours, grease the clutch and brake pedal nipples and the lift hinge points with chassis grease, and grease the top link and lift arm balls.