Your refineries are flashing yellow again. Heavy oil backed up → no light oil → no petroleum → no plastic → no red circuits → no blue science → completely dead base. The fix isn't more refineries. It's three pumps, three circuit wires, and the 8:1:7 ratio that keeps everything flowing.
The Mechanics Behind This Bottleneck
Refineries produce three outputs simultaneously. If heavy oil fills up, the refinery stops — stopping light oil and petroleum production too. The game doesn't prioritize outputs. It stalls everything.
The solution is controlled cracking: convert excess heavy to light, excess light to petroleum, and let petroleum run through to solid fuel or rocket fuel when backed up.
The Proven Fix — Ratios First, Pipes Second
Basic ratio: 8:1:7
| Machine | Count | Purpose |
|---|---|---|
| Oil refineries (basic) | 8 | Raw crude → heavy + light + petroleum |
| Heavy→light crackers | 1 | Converts excess heavy oil to light |
| Light→petroleum crackers | 7 | Converts excess light oil to petroleum |
How the math works:
- 8 refineries produce: 40 heavy + 40 light + 80 petroleum per 5-second cycle
- 1 heavy cracker consumes 40 heavy → 30 light per cycle (clears all heavy if needed)
- 7 light crackers consume 105 light → 70 petroleum per cycle
The system can handle any consumption pattern because the cracking ratios match the production ratios. For a deeper understanding of the circuit logic behind the pumps, see our Circuit Network Guide.
Circuit control (prevents the deadlock):
- Run red wire from heavy oil storage tank to decider combinator
- Decider: heavy_oil > 20000 → output H = 1
- Connect H output to the pump feeding heavy→light crackers
- Repeat for light oil: light_oil > 20000 → output L = 1 → light→petroleum pump
- Set and forget
Understanding Pipe Throughput (The Hidden Limiter)
Pipes have throughput limits that change with length:
- 1 pipe segment: 1,200 fluid/sec
- 10 segments: ~1,000 fluid/sec
- 50 segments: ~400 fluid/sec
- 100 segments: ~80 fluid/sec
For oil processing, keep pipe runs under 30 segments (about 60 tiles). Beyond that, throughput becomes your bottleneck before refinery speed does.
Underground pipes are your friend. Each underground pipe section counts as 2 segments regardless of distance (up to 11 tiles). A 10-tile gap costs only 2 segments instead of 10. This is the single highest-impact optimization for oil pipe networks.
| Diameter (pipe) | Max length before needing a pump | Flow rate |
|---|---|---|
| 1 pipe wide | ~30 segments (60 tiles) | ~80% of max |
| 2 pipes wide | ~50 segments (100 tiles) | ~90% of max |
| 3 pipes wide | ~80 segments (160 tiles) | ~95% of max |
Advanced Oil — Heavy Oil Management
Heavy oil is the most valuable fraction for flamethrower ammo and lubricant. If you crack all of it, you lose access to both:
- Lubricant: Needed for electric engines (purple science). Each engine unit uses 1 lubricant.
- Flamethrower ammo: Heavy oil-based ammo deals the highest damage — see our Flamethrower Defense Guide for turret setup and pipe isolation tips.
The optimal approach:
- Use the 8:1:7 base ratio
- Before the heavy→light cracker, add a split: some heavy oil goes to a dedicated lubricant tank
- If lubricant tank is full (maybe you're not building electric engines yet), route heavy to cracking
- Circuit condition on the lubricant tank: heavy > 5000 → send to cracking
Scaling Up — Refinery Blocks at Megabase Scale
For 1,000+ SPM, you'll need multiple refinery blocks. The design scales linearly:
Your oil products feed directly into blue science, which needs plastic and sulfur—both petroleum-based.
100 SPM base:
- 8 refineries
- 1 heavy cracker + 7 light crackers
- 2 chemical plants for sulfur (plastic + sulfuric acid)
- 1 chemical plant for batteries
1,000 SPM base:
- 80 refineries (10× 8-reactor modules)
- 10 heavy crackers + 70 light crackers
- Dedicated crude oil train station per module
- Circuit control per module (not shared — independent pipe networks)
The per-module design ensures your oil base scales predictably: copy the blueprint, connect a crude oil train stop, done.
Community Verification & Resources
- Official Wiki — Oil Processing — exact cracking ratios and fluid system mechanics
- Factorio Forums — Fluid Mechanics & Pipe Throughput — community testing on pipe diameters, lengths, and flow rates
- FactorioLab Calculator — set SPM target, get exact refinery/building counts including cracking modules
- Kirk McDonald's Calculator — oil processing ratio calculator for any target configuration