Payday 2 is moving to a rebuilt engine called Diesel 3.0, the largest technical overhaul the 13-year-old heist shooter has received. Developer Sidetrack Games spent around nine months rewriting the codebase to push the game onto a 64-bit architecture, switch its rendering to DirectX 11, and shrink the install dramatically. Much of the work happens behind the scenes, but the practical results are fewer crashes, lower memory use, and a far smaller download.
Quick answer: The Diesel 3.0 open beta starts Tuesday, June 30, 2026 on Steam and runs until the end of July. Join it from your Steam library by opening Payday 2’s properties and selecting the engine upgrade build under the “game versions and betas” tab. Expect a full re-download, since the game’s files are being repackaged.
What Diesel 3.0 changes in Payday 2
Lead Engine and Tools Developer Leon Theodoridis describes Diesel 3.0 as “a massive rewrite of the entire code base.” Because so much of it is backend work, you may not notice every individual change while playing, but the cumulative effect touches stability, loading times, file size, and hardware compatibility. The full breakdown of what the upgrade does is below.
| Area | Before | With Diesel 3.0 |
|---|---|---|
| Architecture | 32-bit | 64-bit |
| Memory access | Limited to under 4GB | More than 4GB available |
| Rendering | DirectX 9 | DirectX 11 |
| Install size | 86GB | ~32GB |
| Lobby codes | Longer codes | Six digits |
| Existing mods | Working | Most need repair |
| Open beta | — | June 30, 2026 on Steam |
You can read the developer’s full rundown in the official engine upgrade open beta announcement.
64-bit support ends out-of-memory crashes
The headline change is the jump from a 32-bit build to 64-bit. For years, Payday 2 was capped at the roughly 4GB memory ceiling that 32-bit applications hit, which led to recurring out-of-memory crashes during demanding heists. Theodoridis calls the 64-bit move “by far one of the biggest requests over the last ten years.”
With access to more than 4GB of RAM, the game can hold far more in memory at once. That should improve stability across a wider range of PCs, especially in busy missions packed with enemies, AI, effects, and mods running together. It also gives the modding community more headroom to build larger and more complex projects over time.
DirectX 11 reduces VRAM use, not visuals
Payday 2 is also leaving DirectX 9 for DirectX 11. This is not a graphics upgrade. As Theodoridis puts it, “This will not lead to a visual improvement, but it’ll use a lot less texture memory on your graphics card.” The benefit is efficiency.
Lower video memory usage matters most on older or lower-end GPUs, where limited VRAM can cause stuttering and compatibility issues. With DirectX 11, the game makes better use of modern graphics hardware while giving weaker systems a smoother run, and it leaves more room to raise texture quality without triggering extra crashes.
Install size drops from 86GB to 32GB
Because the engine change already forces a full re-download, Sidetrack rebuilt the game’s packaging and bundling system at the same time. The result cuts the install from 86GB down to roughly 32GB, a 63% reduction for a game that piled up years of DLC, patches, and assets.
Players on smaller SSDs or tight storage gain the most. The studio also recommends moving the game to an SSD if it isn’t already, since faster storage pairs with the shorter loading times the new build targets.
Note: This is not a small patch on top of your current files. Because so much is being rebuilt and repackaged, your existing installation will need a complete download rather than an incremental update.
Mods will break, and how modders can prepare
An engine rewrite of this scale will break most existing mods at first. “With such a substantial engine change, sadly it’s inevitable that some mods will break,” Theodoridis says. The studio is using the beta window to give modders time to adapt.
Sidetrack is encouraging modders to test and repair their creations during the beta, and says it will help with the new file formats the upgraded engine uses. For players who rely on heavily modded setups, that means waiting on updated versions before everything works again.
When the Diesel 3.0 beta starts and how to confirm it works
The open beta opens on Tuesday, June 30, 2026 for Steam users and runs through the end of July. Full instructions arrive at launch, but the beta is expected to be available through the “game versions and betas” tab inside Payday 2’s properties in your Steam library. No console release was announced.
You’ll know the switch took effect when Steam begins a full re-download instead of a small patch, and once installed, the game’s storage footprint should sit near 32GB rather than 86GB. Six-digit lobby codes are another visible sign you’re on the new build. If out-of-memory crashes stop occurring during large heists, the 64-bit move is doing its job.
Payday 2 still routinely peaks around 30,000 concurrent players on Steam, well ahead of its successor, and Diesel 3.0 is aimed at keeping that audience on stable footing for years to come. A full public rollout is planned for later in 2026 after the beta wraps.
