Page 1 of 1
Rapid blackening of Diesel engine oil.
Posted: Sat Mar 01, 2014 3:36 pm
by Entabeni
Entabeni: 2006 Gen3 Pajero 3.2 DiD LWB GLS Auto 204,000km.
Is it characteristic of Diesels that their engine oil rapidly becomes very black? This has been so from when I bought mine in 2010 at 150,000km. Even though it was going extremely well, this had me wondering if the black oil was an indication of a developing crack in a piston that announced itself with white smoke and misfiring in December 2013.
Our son-in law has a 1994 Landrover Defender 2.5 TDI and a 2008 Rangerover 3.6 V8 which has done 100,000km and he says that black oil is normal in Diesel engines. Does any one have a Diesel in which this does not happen?
Re: Rapid blackening of Diesel engine oil.
Posted: Sat Mar 01, 2014 5:25 pm
by andrew.ashton
Hi Entabeni,
It is quite normal, but I believe that it is somewhat dependant on the brand of oil. My understanding is that some oils (detergent types) are designed to keep everything in suspension, some drop particles as sludge.
So for instance Delo 400 can look black within maybe 20 - 30 km from an oil change. But if you look into the cam space below the tappet cover you will see everything very clean (assuming you have been consistently using it).
It is not a sign of looming disaster!
PS How is your engine build going?
Re: Rapid blackening of Diesel engine oil.
Posted: Sat Mar 01, 2014 9:01 pm
by 4ePikanini
When I change the oil I wait until the oil has drained and then sacrifice a liter of clean oil that I pour into the engine and let that drain as well.
My oil stays golden for well over a 1000km.
Re: Rapid blackening of Diesel engine oil.
Posted: Sun Mar 02, 2014 4:26 pm
by Stevevsr
The blackening of the oil in a diesel engine in part is due to the sulphur content of the fuel.
I go to Europe once or twice a year and I always hire a car and 9 times out of ten the hired vehicle is diesel powered and I have noticed that the engine oil is always a lot cleaner than ours here despite the car having several thousand miles recorded on the clock. I may be wrong but I believe the sulphur content on the diesel sold there is as low as .05% ppm as here we have at best 50ppm. I have also noticed that at that lower sulphur levels the engines are a lot quieter than ours here.
The last car I hired (Nov 2013) was a 350AMG C Class diesel powered Mercedes and upon listening to the engine at idle it could well have been a petrol powered car. Someone please correct me if I am wrong in this respect.
Re: Rapid blackening of Diesel engine oil.
Posted: Sun Mar 02, 2014 6:06 pm
by Entabeni
andrew.ashton wrote:Hi Entabeni,
It is quite normal, but I believe that it is somewhat dependant on the brand of oil. My understanding is that some oils (detergent types) are designed to keep everything in suspension, some drop particles as sludge.
So for instance Delo 400 can look black within maybe 20 - 30 km from an oil change. But if you look into the cam space below the tappet cover you will see everything very clean (assuming you have been consistently using it).
It is not a sign of looming disaster!
PS How is your engine build going?
From Entabeni: Thank you Andrew, your comments re dedtergent oils are quite valid. I remember when they became available that there were warnings of clogging of oil passages in old engines when changing to detergent oils. I have used Delo 400 only and at regular 10,000km intervals and new Mits filters.
My son-in-law believes that some agents don't drain the oil completely when servicing client's vehicles but suck out what they can reach through the dip-stick tube! That would leave a lot of old oil to mix with the new --- not a good thing!
I am ready to start reassembling bat am waiting for spares.
Re: Rapid blackening of Diesel engine oil.
Posted: Sun Mar 02, 2014 8:06 pm
by andrew.ashton
Entabeni wrote:
I am ready to start reassembling bat am waiting for spares.
Entabeni,
Have you thought about treating any components before assembly along these lines?
Powerkote. Seems like an interesting prospect.