Caltex Delo 15w40, 5200 miles, Land Rover 4L V8

[landyman]

Second analysis done on this engine... does not look good to me. Engine was overhauled at 199100km, oil changed at 200100. Mileage now 208400, engine in use 8300km (around 5200 miles). I have an engine monitoring system that tells me the engine has been running about 150 hours since the last change.

The overhaul was basically everything - new cylinder liners, pistons, rings, big-end bearings. Injectors were serviced and cleaned.

The previous sample was for only 2000km, and when the engine was using a lot of oil (before the overhaul). The current sample was taken after a long and very dusty 6500km through Africa.

UOA was done at a place called "Wearcheck" in South Africa. They say:
All wear rates are high even for bedding-in. Higher than normal silicon (dust) level in the oil - check air intake system for leaks and for defective oil filler cap, breather or dipstick and dipstick holder. 4.5% Fuel dilution taking
place - check fuel system for malfunction. As a precaution check for low oil pressure. Check that blow-by is not excessive. Change the oil and oil filters. Check oil filter for abnormal wear particles.

(first column is newest sample)
** Wear metals
Iron 44 21
Chromium 10 1
Nickel 1 1
Molybdenum 146 2
Aluminium 16 5
Copper 11 7
Tin 11 1
Lead 112 10
PQ index 10 15

** Contaminants
Silion 31 8
Sodium 22 4
Manganese 9 3
Lithium 3 0
Soot 0 0
Oxidation 19 16
Sulphate 26 25
Nitrates 11 11
Fuel % 4.5 5.5

** Additives & Lubricant condition
Magnesium 315 21
Calcium 2224 2455
Zinc 901 1241
Phosphorous 740 1060
Barium 0 1
Boron 118 2
Sulphur 3832 11570
TBN >6 >6

** Viscosity
cSt 40 degrees Celcius 125.8 80.8
cSt 100 degrees Celcius 15.8 12.2

Obviously the high wear metals, silicon and fuel dilution is worrying me, but what is attributed to recent overhaul and dusty conditions?

Why is the newest sample's viscosity spot-on (it is almost exactly the same as the TDS of Delo 400) with 4.5 % fuel dilution?

 

[landyman]

Phoned the diagnostics department of Wearcheck this morning, and after chatting got the following revised diagnosis:
----------
Wear rates are normal for a unit bedding in but higher than normal silicon (dust) level in the oil - check air intake system for leaks and for defective oil filler cap, breather or dipstick and dipstick holder. Sample contamination suspected due to the high lead figure.
Tests indicate that this oil sample has an unidentifiable volatile component of 4,5%. Check petrol supply for diesel contamination.
----------

Apparently the fuel in my oil is diesel, and since this is a petrol motor it is kind of hard for the engine to be the culprit.

Silicone was used around the sump area to help with the sealing, so it is apparently also possible it is leeching a bit.

I did fill up at some questionable places in Botswana... and lead can apparently still show up in tanks there. The contamination is a possibility because the copper / tin is quite low?

 

[Jim Allen]

FWIW from a "retired" factory (Solihull) trained Land Rover tech, I tend to lean towards the second interpretation of the possibility of a sampling error. Could also be lab error and that's their way of CYA (Cover Your A--).

Other possibilities to discuss:

In dusty conditions, an efficient air filtration system is vital, so if I were you, I would triple check the intake system to eliminate as much silicon as possible. Hose clamps and the fit of the filter into the air box. Maybe even a little air filter sealing grease at all the connections. If you have installed something silly like an oiled cotton gauze filter, replace it with a good cellulose or synthetic media filter. I would also install an air filter restriction indicator (look in the air filter section of BITOG for some tips) and monitor it for restriction, replacing it only when restriction is significant. Depending on what year your Landy is, you may find that the crankcase breather filter up on the rocker cover is inadequate. When I ran Rover V8s in the deserts in the Western US, we found that little foam filter not particularly adequate. As often as not, lots of bouncing worked the cover loose and allowed dirt to be sucked in. Some owners affixed a new barbed fitting to the valve cover and ran a hose to a small remote filter mounted on the firewall. I don't recall the exact filter, but it was something like a small lawn mower would have.

As to diesel being in the oil??? Doesn't seem possible unless diesel was mixed with the gas, or the oil, or we go back to the sampling or lab error possibility. Don't know how new your Landy is but fuel injected Land Rovers in "my" era (late '70s to mid '90s) had particularly inefficient Lucas Hotwire systems that tended to run rich. That could contribute to fuel dilution. Fresh oxygen sensors would help, but if you are running substandard or leaded fuels, they won't stay "new" very long. DIrt ingress from poor air filtration into the air flow meter can contaminate the hot wire there and sometimes cause metering problems.

Still, you are in an area where substandard fuel and less than ideal conditions exist. For that reason, I would recommend shortening your interval a bit (to about 4K miles IMO) until you see some better results. Examine your sampling process for vulnerabilities and correct any deficiencies. I have used Wear Check a few times (they are worldwide) and have little to fault them on based on those experiences.

In your situation, where contamination is hard to prevent, a bypass oil filtration system might also be justified. It would clear the oil of many of the harmful contaminants.

 

[landyman]

Thanks Jim!

It's running a standard paper filter, but I will definitely check out the whole air intake system to make sure it is intact. The crankcase ventilation system on the Disco 2 is from the tappet cover into the plenum, and into the throttle body - will check them too.

The diagnostics guy specifically said the actual petrol in the oil was less than 0.5 % , and the rest of the "fuel dilution" was attributed to "light" and "heavy" diesel in the oil (different percentages as well). On the report it only says "unidentifiable volatile component". I don't really know what to make of that. I can't think of any way that I can get diesel into the oil of a petrol motor!

It is the newest version of the 4L Rover V8 engine, the one with the Bosch management system, and Bosch MAF.

 

[Jim Allen]

Hardly at all familiar with the DIsco II Bosch injection, other than conceptually but less than .5 percent gas dilution is certainly OK so it ain't running rich. As to the unidentifiable components in the oil, it certainly didn't lower the viscosity, so maybe it's nothing more than a one-time anomaly... or a lab error.

 

[Gary Allan]

Pondering this ...since fuel dilution "is what it is", if the fuel was co-mingled with residual diesel/kero in transport, I would think that would have some impact on the UOA. Probably not enough to show deposits on plugs, but enough to stay more stable in oil than lighter gasoline would at normal temps.

 

[FZ1]

What type of AF and OF in each of those runs? Run the best AF and oil filter you can afford to run in those conditions.