Key Differences
| Consumable | Diesel | Petrol |
|---|---|---|
| Engine Oil | Must be DPF-safe (low-SAPS) | Standard spec — less restrictive |
| Ignition | Glow plugs (heat) | Spark plugs (spark) |
| Fuel Filter | Needs regular changing (water separator) | Rarely changed (lifetime fit) |
| DPF | Requires regeneration — affected by oil choice | No DPF |
| AdBlue | Many modern diesels need AdBlue top-ups | Not applicable |
The DPF Factor
The single biggest difference for diesel consumables is the DPF. Using non-DPF-safe oil, short journeys that prevent regeneration, and poor-quality fuel can all lead to DPF failure — a £1,000-2,500 repair. Every diesel car owner should understand DPF maintenance.
Frequently Asked Questions
Is diesel engine oil different from petrol?
Yes — diesel oil for DPF-equipped cars must be low-SAPS (Sulphated Ash, Phosphorus, Sulphur) to prevent DPF clogging. Always use oil meeting your manufacturer’s diesel-specific specification.
How often do glow plugs need changing?
Every 60,000-100,000 miles. Unlike spark plugs, glow plugs only work during cold starting, so they last longer.
