Nissan Navara 23500km ACD 30

[JimmyChainsaw]

Truck has done a further 4488kms for a total of 23668kms on this oil.I was convinced the oil was ready to change so did so at the same time as the sample was taken.Seems like my intuition was wrong!
The usage period was 12 months,motor is a TD27,no turbo,full flow a Repco RZ503,fitted with a MG bypass,which has been changed out every 5000kms.Makeup oil 4 litres.

First column latest result with 23668kms,second last sample at 19180km and last column previous oil change with 20500km.

Cu 2 2 2
Fe 20 15 14
Cr 2 2 2
Pb 4 3 3
Al 3 2 2
Si 2 1 2
Na 4 3 2
Sn 1 2 0
Mo 1 0 0
Ni 0 0 0
Mg 10 9 10
Zn 1270 1237 1193
Ca 3456 3496 3424
P 1032 993 1019
B 2 2 4
Ba 0 0 0
Cd 0.1 0.0 0.0
Mn 0 0 0
Ag 1 0 1
Ti 0 0 0
V 0 0 0
K 1 1 0
W 20.1 26 18.8
NIT 10 10 9
GLY 3 4 3
F 0 0 0
ST 33 33 29
SUL 40 46 40
OXI 44 45 43
V40 89.4 86.8 87.8

Comments;The compartment wear levels and oil condition appear normal,continue to sample at regular intervals to monitor trends.
The reason I changed was I thought the engine was getting quieter and I had noticed the odd puff of smoke from the exhaust at start up.Plus the last report indicated the oil was nearing its use by date and suggested a further sample at 3000km.What surprised me on this sample were the numbers for W,ST,SUL and OXI,all of which I expected to be worse than the last sample.But they weren't,why is that?
The testing lab is Goughs Cat SOS.

 

[m37charlie]

The soot and oxidation and wear metals are accumulating slowly enough so replacing 1L per 5000km with fresh oil keeps up. Try using this oil "forever"; never need to fully change it, maybe change the full flow filter every 30000km. I think you'd find the Fe, soot, Nit, Oxi, Sul etc. will remain constant.
What is your sump capacity? 7L? To do this you need to measure TBN as well.

Charlie