What is the Cat D300 GC?

The D300 GC is Cat's 300 kW value-engineered diesel generator — the top C9 rating in the GC line. At 300 kW standby, it covers the upper mid-range for hospitals, campuses, and manufacturing facilities.

How does the D300 GC compare to the D350 GC?

The D350 GC steps up to the larger C13 engine (12.5L). If 300 kW covers your load with headroom, the D300 GC on the C9 is more compact and cost-effective. If you need growth capacity beyond 300 kW, the D350 GC provides a larger platform.

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Caterpillar · Cat D-Series GC (Diesel)

Cat D300 GC

Name: Cat D300 GC
Brand: Caterpillar
SKU: d300-gc

300 kW standby / 270 kW prime · Diesel · Liquid-cooled

300 kW diesel standby generator from Cat's GC value-engineered line. C9 turbocharged inline-6 with simplified controls for commercial standby.

Cat D300 GC

Specifications & details

Standby power: 300 kW / 270 kW prime
Voltage options: 277/480V, 346/600V
Frequency / Phase: 60 Hz · 3-phase
Engine: Caterpillar C9 · 9.3L
EPA / Emissions: Tier 4 Final

standbyCommercial HealthcaremanufacturingProperty Mgmt

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Overview#

The Cat D300 GC is a 300-kilowatt diesel standby generator — the top C9-powered model in Cat's GC value-engineered line. It delivers the maximum output from the 9.3-liter inline-6 in a streamlined package for hospitals, campuses, and manufacturing facilities.

Top of the C9 range#

At 300 kW, the D300 GC extracts maximum performance from the C9 platform before stepping up to the C13 engine. This makes it the right choice when 300 kW covers your standby requirement — you get a proven engine at a competitive price point without oversizing to a larger platform.

Our service perspective#

The D300 GC runs the C9 at its highest GC rating, so adherence to scheduled maintenance intervals is important. We recommend Cat's S.O.S fluid analysis program to track wear trends. The inline-6 configuration provides straightforward access for service.

Engineering specifications

Physical

Length: 136 in
Width: 56 in
Height: 70 in
Wet weight: 7,400 lb

Fuel system & runtime

Fuel use @ full load: 21 GPH
Fuel use @ 75% load: 16 GPH

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Estimate runtime for the Cat D300 GC

Adjust load percent and tank size to estimate runtime. Pre-filled with this model's spec where available.

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Generator size

Fuel

Fuel tank capacity

gal

Load

Override full-load GPH (optional)

GPH

Estimated runtime

12.3 hours(0.5 days)

Fuel consumption ≈ 16.20 GPH at 75% load. Estimate based on industry-typical 1800 RPM standby curves (≈0.07 GPH/kW at full load). Actual consumption varies by engine, ambient temperature, fuel quality, and tuning.

Service intervals

Manufacturer-recommended intervals for the Cat D300 GC under standby duty. Field intervals may differ based on load profile, ambient conditions, and fuel quality.

Oil & filter: Every 500 hours or 12 months
Coolant change: Every 6000 hours
Air filter: Every 1000 hours
Fuel filter: Every 500 hours
Major overhaul: ≈ 18,000 hours
Load bank test: Every 12 months

Common failure modes

What we've seen fail on this platform. Use as a service-planning reference, not a diagnostic — actual failure modes depend heavily on duty cycle and maintenance history.

Component	Symptom	Typical hours	Severity
Fuel quality	Injector fouling, filter clogging	4,380+	moderate
Turbocharger	Reduced power, oil in intake, turbo noise	18,000+	moderate
Battery banks	Slow crank, failed start	8,760+	minor
Coolant heater	Cold start issues, block heater element failure	10,000+	minor

Frequently Asked Questions

What is the Cat D300 GC?: The D300 GC is Cat's 300 kW value-engineered diesel generator — the top C9 rating in the GC line. At 300 kW standby, it covers the upper mid-range for hospitals, campuses, and manufacturing facilities.
How does the D300 GC compare to the D350 GC?: The D350 GC steps up to the larger C13 engine (12.5L). If 300 kW covers your load with headroom, the D300 GC on the C9 is more compact and cost-effective. If you need growth capacity beyond 300 kW, the D350 GC provides a larger platform.

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