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Old 16th June 2008, 16:23   #16
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during the first service of my diesel Laura, oil was black right after changing it. they said "it is like that only." during the 2nd service, i insisted on oil change in my presence and it was still black. so i stopped worrying about it.

some newer cars tell you when to service your vehicle by sensing things like oil quality/soot level, etc.

OT: Both the skoda service centers here in Bangalore were filling 4.5Liters of oil even though the sump capacity is only 4.3Liters. As a result the oil level exceeds the "max" mark on the dipstick by 2-3mm. They do this because the oil can comes in 4.5Liters standard size. "Don't worry saar" was the standard reply. But I insisted on filling oil while checking the dipstick. Excess oil is bad for catalytic converter (it is written in the manual, oil filler cap and so on.. but they don't care!)
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Old 16th June 2008, 16:43   #17
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Originally Posted by androdev View Post
Excess oil is bad for catalytic converter (it is written in the manual, oil filler cap and so on.. but they don't care!)
Spot on androdev

Excess oil can also lead to oil leaks,lot of smoke in exhaust too.

so always make sure right level is maintained.
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Old 26th May 2009, 18:03   #18
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Default Engine Oil for Diesel cars?

Bhpians, Need help/advice on Engine Oil in Diesel cars. I recently got my car serviced and I was charged for some treatment used while draining the engine oil and was also charged for engine oil.

After driving ~50 Kms I checked my car to see if the engine oil was replaced. The level indicator had dark colored oil and was not translucent. I went back to the service centre and asked if they had forgotten to replace the oil?

The service attendant told me that in Diesel engines, the moment the engine oil is replaced and started, it becomes dark in color. The only way to measure engine oil in diesel vehicles is to check viscosity and not by looking at the colour. Is this true? Can someone with knowledge on this comment?

Last edited by Jaggu : 26th May 2009 at 18:37. Reason: please use search before opening new thread. Thanks
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Old 26th May 2009, 18:27   #19
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For diesel engines, once you start the engine and run it for few KM's, the oil color becomes dark. You will have to check the viscosity as rightly said by service attendant.
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Old 26th May 2009, 18:37   #20
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How much has the engine done so far? and how many kms it ran before you checked the oil after service. Which car is this?
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Old 26th May 2009, 23:57   #21
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Originally Posted by tsk1979 View Post
I changed my car's oil recently and about 200kms after the service I noticed that the color is black from clear oil that it was.
I talked to Tata workshop guys, they checked the oil and said its perfect and after a few kms of driving it goes black.
I did not trust them at all and asked them to show me oil's of some other cars. What I saw in 2 indica's and a safari that barely a few kms after oil change the oil is black. One of the indica's had done just 10,000 kms and had driven just 20kms after oil change!
They told me its the carbon which causes this blackness, and as long as the oil does not become thick, its okay.
Any thoughts about where does all this carbon come from. I change oil every 5-6K kms, and yet there is carbon.
The engine is running fine, good pickup, good mileage and no problem with compression etc., and is definitely not eating oil as there is no smoke too.
Moreover I doubt 3 new cars will have engine problems, so this blackness of oil is a natural phenomena. So can the experts tell me what is the source of this carbon etc.,

Could sulpher be the culprit
API Oil Service Categories
This gives API standards. The latest is CI-4. But all the new ones like CG, CH, CI which can be used in place of CF are for sulpher content below 0.5%. CF grade is for higher sulpher content diesels. So is it possible that using a higher grade oil like API-CG(Shell super diesel) is actually not beneficial as using CF(GTX magnetic, GTD) because CF is designed for sulpher content higher than 0.5%? I am not sure if diesel used in India is high sulpher diesel or Low sulpher diesel.
It is natural for oil to turn black in diesel engines in fact it turn black soon after you change oil.most important is to replace oil filter (high quality) each time you change oil.I have a 1987 merc 300SDL with 110,000 plus miles .i change oil and filter every 5000 miles .the oil turns black soon after it is driven few miles in fact next day or two the oil is black.
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Old 27th May 2009, 00:04   #22
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another reason is all the soot due to the EGR.

when you're recycling the exhaust back into the intake , a lot more soot it bound to get in, and naturally, its the engine oil's job to clean it
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Old 27th May 2009, 00:45   #23
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Diesel engines and their oils are very different from petrol engines. Diesel engines generate more soot (carbon) and this soot is deposited in the oil chamber etc. (see the insides of an opened engine). When oil is drained out, not all of the deposited soot is removed and the remnant immediately mixes in the new oil. This is normal and should not cause concern.

If the discolouration is exessive in the first few Km, try an engine flush with a light oil or an 'engine flush treatment'. This will flush out the deposited soot, reduce the discolouration and increase engine oil life.

Oils in Petrol engines do not discolour as much but will gradually take on a brown to black hue due to trapped carbon and oxidation.

Whether petrol or Diesel, oil has to be changed at or before the recommended drain interval and, earlier if it shows signs of deterioration by the 'sticky finger test'.

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Old 27th May 2009, 00:57   #24
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there are 100 different passages and tunnels and chambers where the oils passes through when the engine is running. and especially in diesel engines its perfectly normal for the oil to turn black within a few 10s of kms after oil change. nothing to be alarmed about.
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Old 27th May 2009, 05:59   #25
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I am totally confused an now my peace of mind has been lost, i gave my jeep for service to a local mech, bought him all the fuel and oil filters and the oil.

I checked the oil after getting the jeep back the oil was black ok no prob the thread explains it all.

But the oil is sticky now i am confused..
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Old 27th May 2009, 07:57   #26
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Even a few kilometers of driving will turn ALL oils dark, even synthetic ones, that too from a petrol engine. The dark colour means that it is doing it's job...removing the harmful byproducts of combustion & storing it. All oils are sticky...they are supposed to be, otherwise how will they stick to the cylinder walls? If the oil starts getting coagulated (thick) is when there is a problem & time for an oil change.

The ONLY reasonable way to make sure that the oil has been changed is be present as it is being done.
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Old 27th May 2009, 08:03   #27
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I recall reading about using compressed air to make sure all the old oil is pushed out. This may help. But as the engine gets older, the carbon inside immediately colors up the new oil. Decarbonisation at recommended intervals helps.
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Old 27th May 2009, 08:07   #28
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I have driven about 3.5k after my last oil change, and the colour is not at all black (still redissh), I guess in Petrol cars oil turns black less compared to diesel cars.
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Old 27th May 2009, 08:46   #29
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It would also depend on how well the car has been maintained. Those engine cleaners (oil flush) help in cleaning up the soot and carbon. But I think its common knowledge that diesel cars get more carbon. Components in the diesel engine are exposed to far higher pressures and temperatures than the components in gasoline engines. This can also be a major factor if you are comparing between the two engines.
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Old 27th May 2009, 09:03   #30
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Diesel engines will have the oil go dark pretty fast. There is a lot of carbon deposited in the engine as a routine, which is removed by the oil. This is the reason that diesel oils have far more of detergent than petrol oils.

Oil in petrol engined cars goes dark much more slowly (very little carbin deposited). In both my cars even after 5000 km the oil is somewhat discoloured by not black.
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