Yanmar GK13–GK18 Engine Oil and Fluids: What Goes Where?

Which engine oil belongs in a Yanmar GK13, GK14, GK16 or GK18? And which oil in the transmission, front axle and cooling system? The GK-series factory manual is clear about this — in this article you'll find all prescribed fluids, exact capacities and practical refill instructions.

Suitable for the entire series: Yanmar GK13, GK14, GK16 and GK18 (Ecotra), plus the European versions GK160 and GK200(R).

Yanmar GK13–GK18: Prescribed Fluids

Yanmar GK13–GK18 Engine Oil: 10W-30 as the Base

Yanmar prescribes a 10W-30 diesel engine oil of at least API CD quality. The 3TNV70 and 3TNV76 are swirl-chamber engines without a soot filter, so a modern CF/CI-4 oil is also fine — higher is fine, lower is not. Our mini tractor engine oil 15W40 (SKU-15W40) meets API CD and is an excellent choice for the mowing and working season in the Dutch climate; if you regularly work in frost, stick with the thinner 10W-30 from the manual for easier cold starting. Change every 100 hours or annually — whichever comes first — and replace the oil filter (OEM 119305-35151, M20×1.5 thread) every 300 hours.

Here's how to change it in practice: run the engine until it's hand-warm, remove the drain plug, collect the oil, unscrew the filter counterclockwise with a filter wrench, lightly oil the rubber ring of the new filter and fit it hand-tight. Fill up, start the engine until the oil pressure light goes out, then check the dipstick once more.

Yanmar GK13–GK18 Transmission Oil: One Oil for Gearbox, Lift and Steering

The transmission, hydraulic lift and power steering all share the same 7 liters of oil. Yanmar prescribes TF-500 transmission fluid; use an equivalent UTTO/transmission fluid and never regular engine oil. Change it for the first time after 50 hours and then every 300 hours, at the same time as the transmission oil filter behind the two-bolt cover (OEM 198421-24910). A clogged filter shows up immediately as a slow or hesitant lift — it's one of the first things to check for lift problems. After refilling: let the engine idle so the oil circulates, then check the dipstick.

Yanmar GK13–GK18 Front Axle Oil: The Forgotten Liters

The driven front axle has its own oil supply: 2.4 liters of EP 90 gear oil. This is often overlooked because it's out of sight, but the manual calls for fresh oil every 300 hours (first change already at 50 hours) and a level check every 50 hours in between. This is especially important on machines that work a lot with a front loader or in wet terrain: condensation in the front axle turns the oil milky.

Yanmar GK13–GK18 Coolant: Replace Annually

The cooling system is small (3.3 liters total) and the manual prescribes annual replacement with permanent antifreeze. Use our ready-to-use coolant down to -40 °C (SKU-125001); on a machine with an unknown history, it's wise to first flush the system with radiator flush (SKU-125007). Don't forget the radiator screen — cleaning it every 50 hours prevents the most common cause of overheating.