I know that most manufacturers have their own color of the diesel engines, but it applies to boats to know which one is whose. Maybe in the car industry, the one color makes easier to spot leaks or other problems with it. I suppose in gas engines it's hard to spot any problem based on the color...
That would be useful for me as well. I'm looking for an engine for a BMW e32. But like in a great condition. I'm not sure if I'll be able to find anything for a normal amount of money. Usually, prices are way too high.
As I have an old car I used to change the oil every 4000 miles. After a few years, I now change oil every 2000 miles. I think I need to change something in my car. But I'm not an expert, often I just use car service.