A Fleet Manager's Guide to Transitioning an Entire Fleet to R99

Switching an entire fleet to renewable diesel is a bigger decision than filling up with a different fuel one time. It touches procurement, maintenance schedules, driver communication, and — for many fleets — sustainability reporting. If you're a fleet manager considering a full transition to R99 renewable diesel, this guide walks through what the process actually looks like, so you can plan the switch with confidence.

What Is R99 Renewable Diesel?

R99 is a renewable diesel fuel made primarily from renewable diesel with a small blend of conventional diesel. Renewable diesel itself is chemically different from biodiesel: while biodiesel is typically blended with petroleum diesel (like B20 or B99), renewable diesel is a hydrocarbon fuel that is chemically similar to petroleum diesel. This is what allows it to be used as a "drop-in" fuel in most existing diesel engines, without engine modifications or blending limits.

Because it meets ASTM D975 diesel fuel specifications, R99 can generally be used in the same tanks, pumps, and vehicles as petroleum diesel.

Why Fleets Consider Switching to R99

Fleet managers typically explore a fleet-wide switch to R99 for a combination of reasons:

• Emissions reduction: Renewable diesel is associated with lower lifecycle greenhouse gas emissions compared to petroleum diesel, which supports company sustainability goals and public-facing climate commitments.

• No engine or infrastructure changes required: Because R99 is a drop-in fuel, fleets can typically switch without replacing vehicles, modifying engines, or installing new fueling equipment.

• Compatibility with existing maintenance schedules: Since R99 meets the same diesel fuel specification as petroleum diesel, it doesn't require a separate maintenance protocol.

• Regulatory and reporting pressure: Fleets operating in California, particularly those serving government contracts or public agencies, are increasingly expected to show progress on emissions reduction.

Step 1: Confirm Manufacturer Approval for Your Vehicles

Before switching any vehicle to R99, check with the original equipment manufacturer (OEM) to confirm the engine is approved to run on renewable diesel meeting ASTM D975. Most major diesel engine manufacturers have approved the use of renewable diesel in their engines, but approval can vary by engine model and year, so this step should never be skipped. Your fuel supplier should be able to help point you toward manufacturer documentation if you're unsure.

Step 2: Decide Between a Full Switch or a Phased Rollout

Fleet managers generally take one of two approaches:

Full fleet switch: All vehicles transition to R99 at once, typically during a scheduled bulk delivery or tank refill. This works well for smaller fleets or fleets with a single fueling location.

Phased rollout: A subset of vehicles — often a specific depot, route, or vehicle class — switches first, with the rest of the fleet following over a set timeline. This approach is common for larger fleets that want to monitor performance before committing every vehicle.

There's no universally "correct" approach — the right path depends on fleet size, number of fueling locations, and how much oversight your team wants during the initial transition.

Step 3: Plan for Fuel Storage and Delivery

If your fleet uses on-site fuel storage tanks, confirm with your supplier whether any tank preparation is needed before switching to R99. In many cases, tanks previously used for petroleum diesel can be used for R99 without modification, but it's worth a direct conversation with your fuel provider to confirm based on your specific tank setup and fuel history.

If your fleet doesn't have on-site storage, this is also a good time to evaluate mobile or wet-hose fueling, which allows R99 to be delivered directly to vehicles without requiring a storage tank at all.

Step 4: Communicate the Change to Drivers and Maintenance Staff

Because R99 performs similarly to petroleum diesel, most drivers won't notice a difference in day-to-day operation. Still, it's worth briefing your team so that:

• Drivers know the fuel type has changed, in case they're asked or need to log it

• Maintenance staff are aware of the switch, in case it comes up during routine service or troubleshooting

• Anyone responsible for fuel purchasing or reporting has accurate records of the transition date

Step 5: Track the Transition for Reporting Purposes

If your organization tracks fuel-related emissions data for internal reporting, customer requirements, or public sustainability commitments, document the date your fleet transitioned to R99 and the percentage of your fleet running on it. This creates a clear record you can reference later, without needing to reconstruct the timeline after the fact.

Common Questions Fleet Managers Ask Before Switching

Will R99 void my engine warranty? This depends on your specific engine manufacturer and model. Because R99 meets the same ASTM D975 specification as petroleum diesel, most major manufacturers permit its use, but you should confirm directly with your OEM before switching.

Do I need to blend R99 with petroleum diesel? No blending is required. R99 is designed to be used as a standalone drop-in fuel in approved engines.

Can I switch back to petroleum diesel later if needed? Yes. Because R99 is compatible with the same tanks and engines as petroleum diesel, fleets can generally switch back and forth as needed without equipment changes.

Making the Switch with Dogpatch Biofuels

Dogpatch Biofuels supplies R99 renewable diesel to commercial fleets throughout San Francisco and the greater Bay Area, along with bulk delivery and mobile fueling options to fit fleets of any size. We work directly with fleet managers to plan transitions — whether that's a full fleet-wide switch or a phased rollout — and help confirm fuel storage and delivery logistics along the way.

Considering a fleet-wide switch to R99? Contact Dogpatch Biofuels to talk through your fleet's vehicles, fueling setup, and timeline.