Lab comments: (Predictive Maintenance Service for all tests)
Dirt (silicon) continues to decrease, however there is a slight increase in copper (first limit = 20ppm). Oil viscosity is high with the maximum limit for SAE 40wt oil as 16.3 Cst. In addition, the TBN value is low compared to previous tests. All other things being equal, I would say that you have reached the maximum mileage on your oil, and may want to consider cutting back the interval between oil changes.
I'm surprised the viscosity went up so high and the lead was as high as it was.
Dirt (silicon) continues to decrease, however there is a slight increase in copper (first limit = 20ppm). Oil viscosity is high with the maximum limit for SAE 40wt oil as 16.3 Cst. In addition, the TBN value is low compared to previous tests. All other things being equal, I would say that you have reached the maximum mileage on your oil, and may want to consider cutting back the interval between oil changes.
I’m going to pull the plug on this 10w40 experiment. I refilled with 10w40 but I’ll dump it and refill with 10w30 at the end of the summer (about 5k miles).code:
2003 Honda Civic 6/29/2003 9/14/2003 5/31/2004
Total Miles 1643 4634 15709
Miles on Oil 1643 2991 11075 New
Oil factory fill Redline 10w40 Redline 10w40 Redline 10w40
Iron 18 12 19 1
Cr 0 0 0 0
Pb 12 6 31 0
Cu 10 15 25 0
Sn 13 18 19 17
Al 18 12 19 2
Ni 0 0 0 0
Ag 0 0 0 0
Si 81 32 21 16
B 38 6 2 1
Na 11 45 65 69
K 4 16 6 3
Ca 2134 2569 2490 2686
Mg 14 14 14 13
P 1065 1616 1732 1783
Zn 1172 1608 1707 1792
Mo 517 994 1007 1094
cSt@100C 7.7 13.6 18.2 14.5
fuel Absent Absent Absent Absent
water
Glycol N N N N
Soot 0.2
Oxidation 10.9 85.0 91.0 82.0
Nitration 5.2 10.0 15.6 6.0
TBN 6.0 6.8 2.9
I'm surprised the viscosity went up so high and the lead was as high as it was.