Originally Posted By: zeng
Originally Posted By: 09_GXP
Diesel's have different emissions equipment that isn't harmed as easily from the additives in oil.
Pre-CI4 HDEO's already possesses higher quantity of antiwear additives than a PCMO, when EGR/SCR/DPF wasn't available yet.
EGR was in use before CI-4 was invented, it just wasn't in used OTR trucks. Most cars and light trucks had an EGR valve since the 1980s.