Given below is medium speed trunk type main engine system oil analysis report, with reference to each parameters of this report-

a)  Is there sufficient additive reserve in circulation oil to protect the engine?

b)  Analyze the condition of this oil from used oil test results for each parameter by comparing with SAE30 new oil

c)  Discuss the effect of continued usage of this oil in the system without taking any corrective measure

d)  What lube oil system adjustment and treatment is required for continued usage of this oil and safe operation of the engine

a) sufficient additive reserve in circulation oil to protect the engine

From standard guidance the oil volume in the sump should be 1 .3kg/kW (4 strokes), in this case for an engine rating of 7200kw, the volume should be 7200X1.3=9360 kg or   9360/0 .95=9856 litres, But the present reserve is 5000 ltr which is half of the required volume, there is not sufficient additive reserved to protect the engine during its operation.

b) Analyze the condition of this oil

Viscosity: 

Viscosity has increased due to-

• High insoluble content
•  HFO contamination due to leaky injectors, worn fuel p/p plunger & barrels
• Piston blow past
• Oxidation due to ageing & high operating temp
• Water contamination (emulsification)

For information: viscosity can decrease by gas oil contamination during prolong running in ECA area.

Density: 

Density has increased due to-

• High insoluble content
•  HFO contamination due to leaky injectors, worn fuel p/p plunger & barrels
• Piston blow past
• Water contamination (emulsification)

Flash point:

Flashpoint has reduced, Main suspect FO contamination due to

1. leaking injectors, improper combustion, blow-past,
2. worn fuel pump plungers & barrels
3. Min. 180 deg C

Water:

Presence of water with trace of chloride Due to

• Bilge leakages likely through
  • sump level indicator
    • damage diaphragm between sump and engine
• Crankcase breather pipe condensation as atmosphere has saline nature
• Inefficient operation of purifier
• Possible but do not suspect leakages due to steam or engine cooling water leakage as this may increase the base number
• allowable FW content max 0.2%, for short period 0.5%

Trace of Chloride:

• Not a sign of contamination
• Inevitable due to nature of sea environment

Ash: 

Increase due to –

•   HFO contamination due to leaky injectors, worn fuel p/p plunger & barrels
•   Blow past
•   Rust in the sump tank

Base number:

Reduces due to                   

• Insufficient oil volume in circulation  
• Irregular top up of sump
• Fuel contamination and sulphur in HFO can reduce TBN
• Max +100%, min -30% of initial value.

Insoluble: 

The amount of insoluble ingredients in the oil is checked as follows.

• Equal parts of oil samples are diluted with [Toluene/benzene] and [pentane / heptane].
• As oxidized oil is only soluble in benzene and not in pentane or heptane the difference in the amount of insoluble is indicatives of the degree of oxidation.

Pentane /heptane Insoluble:

• Indication of oxidation & the metallic deposits/ solid contaminant present
• Max 2% 

Toluene/ benzene insoluble:

• Indication of the solid contaminants
• Max 1%

P/H –T/B insoluble:

3 –1.5 = 1.5 is the Indication of the rate of oxidation that has taken place

Limit max. 1%

Main possibility due to:

• Insufficient volume
• Improper top-up
• Ageing of oil

c) Effect of continue use of this oil.

1. Due to increase in viscosity & density-
2. LO film will be Affected
3. Hydrodynamic lubrication properties can be affected, and bearings can experience higher wear
4. Ineffective purification due to change in density without adjusting gravity disc 

2. Due to lower flashpoint, cylinder lubrication oil film formation will be affected

3. Presence of water can lead to emulsification & trace of chloride can lead to high temp corrosion if HFO containing vanadium

3. Ash has effects of

• Abrasive wear
• Micro seizure and scuffing

4. Lower TBN value can lead to acidic corrosion at liner surfaces.

5. Presence at insoluble can lead to FPS

• foaming of the lube oil
• pitting on the bearing surfaces
• Scoring on the bearing and journal surfaces

6. High degree of oxidation can lead to varnish deposition

d) Adjustment and treatment:

• Carry out batch purification at first opportunity including cleaning of Sump, this will reduce the water & insoluble content.
• Fuel & water leakage should be identified & rectified
• Run Centrifuge at optimum throughput & maintain temp at 85-90°C
• Sump tank should be filled to the right volume and then regularly top up of sump at 40 litre/day to match consumption
• Samples sent for lube oil analysis for follow up action

Carry out spectrographic analysis if available