I would like to know how can lubricants lose its volume over time in a car engine? Our customers complained that after like 5000 km, there's a loss of 1-2 liters of engine oil (SAE 20W-50), isn't it too much? They also said that after a few weeks, they have to top up the oil. Can someone tell me what is wrong? My company does lubricant blending and this has never happened before.

Hello Hazel,

Because you said our "customers" then I'll assume that the condition is not isolated to 1 engine burning the oil. So the most likey cause is that you have blended a base oil with a high volatility level. Basically the oil shears down and evaporates. As you get air porting through the engine in the valve train etc the air picks up the vapourised oil and the next you know the EGR system is picking up the oil and it goes through the combustion process and out through the exaust.
There is a QA test that you should be performing the NOACK Volatility test ASTM D-5800. You can read up a bit more here...
http://www.1st-in-synthetics.com/10W30APIc.htm

So you need to get your purchansin group to specify an acceptable volatility level when you buy your base stock.

regards.........

Hazel,

Lube loss (or higher consumption) can be for two reasons rightly mentioned by Alan in his post.

1. High volatile content in the oil.
2. Oil leakage ( Stupid reason, but true )

I would like to share an interesting experience in Castrol India which would be an eye opener. In the mid 90's Castrol launched a new series of value for money Engine oils named "CRD 40 Xtra" & "CRD 30 Xtra". Initial complaints from users( 10 or 12 Ton Lorry (or Trucks) was high consumption.

In all probability somebody forgot to compare Novack Evaporation loss tests. After a while better sense prevailed and tests and analysis conducted the complaints disappeared.

Many years later when I was talking to a Production Chemist on this complaint, his answer was an eye opener. He said initial blends of CRD 40 Xtra was nothing but CRD 30 Xtra with viscosity boosted to CRD 40 Xtra, in house blending of SAE 30 was done with lower viscosity oils and then viscosity boosted to SAE 40. That it was a value for money product a component of recycled oil may also have been added.

All in all the lighter ends of SAE 30 resulted in higher consumption and this was subsequently corrected.

In conclusion, a refinery SAE 30 or SAE 40 would be more compact and would have evaporation loss in line with standard permitted. In house blending ( say combinations of SAE 10, SAE 20, with SAE 40 to arrive at SAE 30) would have higher volatility and hence evaporations loss higher.

Hussam Adeni

Hazel,

Apart from Volatility and external oil leakages,
Wornout Liners,Rings allows oil to get burnt in
combustion chamber.If engine is turbocharged,
engine oil loss is through external and internal seal leakages.

Inadequate oxidation and thermal stablity of oil
losses its property over a period of time and
could lead to high oil consumption,increased wear.

Do Oil analysis to confirm machine condition,
contaminant condition and oil condition.

Bala.

hi
the discussion is very informative.however are there are standards which provide lube loss/consumption levels vis-a-vis the engine hp and also engine life?

Sam,

Evaporative loss is measured by the Noack Test as percentage ( % ) loss by wt. For Diesel and Gasoline engines the values for MIL and API are given below:

1. For diesel engines - MIL-2104G

a)For 10w allows 18% loss by wt max.
b)For 5w/30 allows 20% loss by Wt Max
c)For 10w/30 allows 17% loss by wt max
d)For 15w/40 allows 15% loss by wt.

2. For Gasoline engines - API SH and SJ

a)For SAE 5w/xx allows 25% (SH) & 22% (SJ)
b)For SAE 10w/30 allows 20%(SH) & 22% (SJ)
c)For SAE 15w/40 allows 18%(SH) & 20% (SJ)

The standards are based on oils (or base oils in use).To correlate to horsepower we will have to seek info from the OE's. But I trust the info above is suitable.

Hussam Adeni

Sam,

Lab Noack evaporative may meet the spec.However
Lab conditions and field conditions are quite
different.Oil should pass the field conditions.
Certain oils forms excess deposits in combustion
chamber and piston grooves,land areas,eventually
leads to high oil consumption.

Bala.