The mobil Delvac is dino, i use a lot of mobilgard 450, high tbn, @14, couse the sulfur content of diesel in this country is very high.
Any ways i have to keep track of a fleet of 25 units, crew boats and tog boats, as you can imagine i do usu a lot of oil, @ 15000 gallons a year, so oil is a very high expense for me. Since I buy mobil, they let me test the oil for free, so you can´t imagine the amount of test i do a year, and for any thing that crosses my mind. Needles to say i am kind of disapointed at Mobil 1, very low TBN for very few milles.
Actually a have te results foa an A160 mercedes, Mobil 1 did a lot better on that one.

The oil on the A160 had 7500 milles, the car had 15500 milles
Note the fuel in the oil.

104105 T.B.N. De Aceites Usados ASTM D 4739 mgKOH/g 3,00
750032 Viscosidad Cinematica 100°C Ac. Usado NVC 424-91 cSt 16,04
750041 % de Agua por IR Aceites Usados NVE 751-96 % p/p 0
750042 Oxidación por IR Aceites Usados NVE 751-96 A/cm 6,25
750045 Combustible por IR Aceites Usados NVE 751-96 % p/p 19,42
750046 Glicol por IR Aceites Usados NVE 751-96 % p/p 0
750047 Hollin por IR Aceites Usados NVE 751-96 A/cm 0
750161 Fe NVE 135 ppm 20
750162 Cr NVE 135 ppm 4
750163 Pb NVE 135 ppm 201
750164 Cu NVE 135 ppm 6
750165 Sn NVE 135 ppm 6
750166 Al NVE 135 ppm 22
750167 Ni NVE 135 ppm 2
750168 Ag NVE 135 ppm 0
750169 Mo NVE 135 ppm 2
750170 Ti NVE 135 ppm 0
750171 V NVE 135 ppm 1
750172 Si NVE 135 ppm 12
750173 Na NVE 135 ppm 11
750174 B NVE 135 ppm 35
750175 Mg NVE 135 ppm 1463
750176 Ca NVE 135 ppm 992
750177 Ba NVE 135 ppm 0
750178 P NVE 135 ppm 942
750179 Zn NVE 135 ppm 1220

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89 560SL
78 172N
01 CBRXX
98 EV11