Originally Posted By: dnewton3
allan5oh might be onto something here.
The CJ-4 spec is certainly geared towards today's newer exhaust controlled, DPF type vehicles. I know from reading on the Rotella, Delo and Delvac pages that the products are aimed squarely at controlling soot better than previous generations.
It's possible that these new formulations are going "look" different visually, because they're now picking up soot in quantities that previously had been allowed to drop out. Now, they are holding it in suspension better, and therefore the appearance of the oil is going to be different.
Further, after the trip, if you continued use of the same oil, would the GC bypass filter eventually clean the soot from the oil? Since there is likely more in suspension, it might take longer to get it back to some state that you visually recongnize.
Let's also remember that since CJ-4 was primarily biased towards the emmisions-control aspect of oil, that other characteristics were only slightly changed, even if not by intent. I.E. - the lubricating properties and emmision control properties of CJ-4 over CI-4+ have been touted by all the major companies. But heat control wasn't part of the EPA mandate, and therefore there's no reason to think that the characteristics of heat tolerance have changed much, if any.
It makes sense to me that, while you're attributing the visual changes of the oil to a percieved increase in heat, it's more likely that increased capability of soot suspension is the real cause of the changes you see.
While you are correct about the oils characteristics with regards to soot handling, even my GCF will not bring the oil "back to life" after this perceived "damage".
And to add, the viscosity increased (in the previous sample) while insolubles remained the same as always (0.3%). Neither time it has happened has the GCF been able to bring the oil back.
I do not think soot is my problem...if it was, my oil should be fine right now as that 100 mile run was over 1500 miles ago...the oil has not improved. And if it was soot, then I should have seen a significant spike in the insolubles in the UOA that also had increased viscosity, right?
I'm only perceiving what causes it to change...higher RPM, higher than normal load, higher EGTs. I am not pointing at one single thing, but I feel of the things that could damage oil in a Cummins, heat is probably the most likely suspect in my case...