How long should the oil, after an oil change, stay that nice new browny colour - before it turns to good old black? 2002 Honda VFR800
2002 Toyota Celica 140 Silver (mid life crisis - again!)
2007 FL2 GS Manual Army Reconnaissance Green + freel2.com sticker
2004 Toyota Celica 140 Black - Gone
2000 Toyota Celica 140 Silver - Gone
1998 Toyota Celica ST Pearl Green - Gone
1996 Nissan Primera 1.6 - Gone
1994 Rover Montego 1.6 Auto - Gone

In a diesel you will be lucky if it stays brown for a day. It quite normal for the oil to turn black almost straight away

Even after a flush it turns black very quick.

About a minute, until all the oil's been around the engine once! Mine: 2012 Golf GTI Edition 35
Family's: 2009 Freelander 2 HSE TD4 Auto, Stornoway

Yorkshire - God's County

Yep, agree.

Thats why intermediate oil changes are good for diesel engines... 2010MY Freelander 2 HSE Auto
Santorini Black with Ebony Napoli Leather

Everyone to their own, personally I think it's a little pedantic.

The color of the oil has no bearing on its lubricity or whether its any good or not. All diesel engine oil will turn black in the first few hours because of the contaminates generated by combustion and the soot particles. The oil filter will take out the larger sized soot particles that can cause engine wear and the additives in the oil are supposed to hold the smaller soot particles in suspension, its these particles that change the colour of the oil.

It still does no harm to change it as often as you like though.

The oil will turn black quite soon, depending on the engine parameters. As a chemical engineer working for years in the lubricant industry I could tell that the main role of a lubricant is, Reduction of friction, Protection against wear, Protection against corrosion, Heat transfer, Cleanliness and soot suspension in internal combustion engines and of course Fuel economy. All of the above is done through good base oil and proper additive selection.

A black oil is good! It means that the lubricant cleaned the engine and kept soot in dispersion. Which means when you drain the oil all the impurities will go out from the engine. When the lubricant after use has a nice brown color, it means that all the bad oxidating stuff is still inside the engine.

As far the oil changes, you should always follow the manufacture’s recommendations. Now days lubricants they have special alkaline additives to neutralize the acids produced during combustion for many many miles driven. If you change the oil e.g after 1000miles for a long period time you may destroy the cylinder surface from the alkaline additives (is rare but could happen).

Just my two cents…

I had a new Disco in 2006 and the oil stayed clean for months.Could it be because they have 2 oil filters? Stornaway grey SE auto with 18" alloys

In a virgin engine, indeed the oil is clean for a period of time until the soot accumulates.
But then it will change to black and stay in that way.
Even after an oil change it will turn black pretty soon, a good part in this process taking the fact that when you change the oil a considerable quantity of the old oil (aprox. 10% and sometimes more) remains in the upper section of the engine. In the FL2 case, more than 0.6 liters of the old oil remains inside.
This old oil quickly contaminates the new oil, new oil that in the first hundreds of miles, because of the detergents additives inside, cleans the interior of the engine - another reason for turning black.