Why do HDEO's have more anti wear additives?

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Also, Maybe more bondary layer regime at diesel low rpms @ huge loads. Higher viscosity burn less and so, less metalic ash is produced. Different regulation.
 
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A while back, there was a real problem of cross-head wear on one of the Cummins HDD oil qualication tests. It was never something I dabbled in but I might imagine that a decently high slug of ZDDP was needed to fix the problem.
 
Originally Posted By: 09_GXP
Diesel's have different emissions equipment that isn't harmed as easily from the additives in oil.


This and they are typically used under high stress/high heat situations. Also they are listed for longer oil drain intervals than most standard gasoline engines
 
So if i understand it correctly a higher concentration of antiwear additives such as zddp won't offer more protection but it will extend the time that they work as they are used up?
 
And Mobil, Schaeffer and some others are using more moly in their oils. CJ-4 did take a bit of a bite out of ZDDP, not nearly as much as PCMO's were affected.
 
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.
 
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.
 
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