Roger:
Sorry about the confusion. First of all, your original question had to do with cold temp performance, especially at -25C and colder, not with UOA and TBN's and such.
I apologise if my original statement about Delvac 1 offering superior cold temp performance confused you. My Delvac 1 spec sheet was over a year old, and at the time Delvac 1 did offer superior cold temp performance.
When another forum member challanged my assertion, I though he had used the wrong numbers, as the pour point didn't sound right. A quick check at the Mobil web site proved I was wrong about the "new" Delvac 1.
With the CI-4 reformulation, and based on what limited spec Mobil does publish, Delvac 1 no longer appears to offer good cold temp performance colder than around -30 C.
Also, unless you're willing to invest in bypass filters and a fairly tight regime of UOA, Delvac 1 does NOT pay. I have also sent you emails stating this, and I recommended a far cheaper alternative.
In such a case, Esso XD-3 meets or exceeds deposit control when kept to the factory recommended OCI. The Esso XD-3 was the first of the major HDEO's blended to control Top Grove Fill, which the Cat 3116 motor, along with other diesel motors, experienced.
I have used Esso XD-3 in the past and would have no hesitation to do so again. Their products are engineered and blended for true Canadian environments, and currently exceed all North American HD specs required by Cat, Cummins, Detroit Diesel, Mack, and Navistar.
Since Esso is quite willing to share all their test data, which you can find at
www.imperialoil.ca, the cold temp performance of Esso XD-3 0W-40 and 0W-30 is apparent.
When compared to the few test points from Mobil, here is how they compare:
CCS at -30C:
Mobil Delvac 1 5W-40 CI-4 rated: 6,100 cP
Esso XD-3 0W-30 CI-4 rated: 5,900 cP
Esso XD-3 0W-40 CI-4 rated: 5,900 cP
Pumping Viscosity at -35C:
Mobil Delvac 1 5W-40 CI-4 rated: 32,000 cP
Esso XD-3 0W-30 CI-4 rated: 11,200 cP
Esso XD-3 0W-40 CI-4 rated: 14,900 cP
Especially in the cold temp flow test, MRV, Esso XD-3 in either 0W-30 or 0W-40 offers FAR superior performance over Delvac 1. I emailed you a detailed test result and suggested you contact your Cat authorized engine shop for more advice.
You have stated reluctance to move beyond a 15,000km OPI, which would make Delvac 1 a VERY expensive oil to use. I'm not in the habit of twisting someone's arm to extend OCI's.
For an expensive diesel motor, extending the OCI out 4-6x recommended (The point where Delvac 1 makes sense) carries a lot of risk and should NOT be taken lightly. At the very least, the primary and bypass filters must be carefully considered, and UOA is a must.
Remember that unlike passenger car oils, HD diesel oils are not subject to CAFE, "Starburst" or other such nonsense. The engine maker can and does have an Approval List and you should always use an oil on that list.
With appropriate OCI's, Esso XD-3 will keep a motor clean and provide good service. Now for winter temp performance, I may have to switch my entire fleet back to Esso XD-3.
I've noticed at -42 unless I use the electric pan heaters, the Delvac 1 appears to be sluggish. With XD-3 0W-40, that would NOT happen, as the MRV values are less than HALF the "new" Delvac 1.
Shell also offers a good oil, but it's not "better" than Esso XD-3 and costs more. All the fleet owners and loggers around here who do NOT run synthetics run Esso XD-3 with good results, as long as they run the viscosity appropriate for the ambient conditions.
In the end, you've also discovered just how confusing picking an oil has become. It caught me by surprise as I assumed the "old" Delvac 1 and the "new" Delvac 1 rated the same in cold temp. They don't.
Jerry
