Why does nobody talk about how much oil residue builds up in aftertreatment systems from short-haul routes

I was reading a SAE paper last night and it said 70% of DPF failures come from trucks that never get fully up to temp on regular runs. My buddy runs a local delivery fleet and has been pulling clogged filters every 8 weeks - anyone else see this pattern in their shop?

3 comments

3 Comments

roberts.leo1mo ago

Is it really that simple though? If highway loops were the magic fix, every short-haul fleet would already be doing them and nobody would be complaining. The 70% number from the SAE paper is interesting, but take it with a grain of salt - those studies are usually funded by the parts companies selling the filters or the additives to clean them. I bet you a majority of those failures are from poor driving habits or just straight up bad maintenance schedules, not the trucks not getting hot enough.

jamie_adams1mo ago

I mean that 70% number tracks with what my buddy at the courier service saw. He was swapping out soot-loaded filters every other month until he started forcing them on a highway loop once a week just to burn it off.

michael_green441mo ago

That "highway loop once a week" thing is smart but most fleets don't have a loop handy or the driver's going to fight it. I've seen guys log a 10-minute idle cooldown as "highway miles" just to hit their numbers. The real issue nobody talks about is the regen cycle itself gets programmed wrong from factory. Had a '22 model that would only start regen at 600 degree exhaust temps but the gearing kept it at 450 on my local routes. Bought a cheap pyrometer and the DPF clogged twice before I reprogrammed the threshold.