Higher sulfur diesel in waivers risks engine degradation for Tier 4 engines

Using 500 ppm sulfur diesel in newer engines (Tier 4 and Tier 4 Interim) causes gradual component degradation due to exceeding their 15 ppm sulfur limit.

Sulfur content limit

15 ppm for Tier 4 engines

Waiver sulfur content

500 ppm in Texas/Alaska

Affected engine tiers

Tier 4 and Tier 4 Interim

Degradation timeline

Continuous use causes gradual damage