This is what the color of your engine oil can tell you – Jalopnik

This may sound like something out of the original TV series “CSI: Crime Scene Investigation,” but you can tell a lot about the health of the engine by pulling out the dipstick, reading the oil level and checking the color of the oil. For starters, you need to be on top of it if a previously full oil pan suddenly becomes nearly empty, which likely means your engine is leaking or guzzling oil. The problem is made worse by the possibility of an illuminated or flashing oil warning light, and that means you should immediately stop driving and call for help.

When it comes to color, there is a myth that dark oil is dirty and should always be replaced immediately. When talking about diesel engines, dark or black oil is common because oils for diesels contain more detergents or cleaning additives. In short, dark or dirty looking oil in a diesel is nothing to worry about in most cases and simply means that the oil is doing its job of cleaning and protecting the internal parts from damaging friction and excessive heat.

The situation is similar with gas engines. Fresh oil starts out as a slightly transparent and gold-colored liquid, but eventually darkens or discolors as it circulates in the engine. Modern motor oils contain vast amounts of additives that contribute to color change by absorbing heat, oxidation and combustion byproducts with each revolution per minute (rpm), meaning dark brown or light black oil in a gas engine can be a sign that the oil is performing as intended.

What this means is that if the oil is dark or turning black and it has been six months or more since your last oil change, the oil may be close to being too dark and the oil needs to be changed. Be warned, however, if the dark oil contains clumps of dirt or visible sludge, which looks like a buildup of cholesterol in your arteries. Sludge builds up if you don’t change the oil regularly, the engine suffers from overheating, persistent misfires or other internal problems.

Again, don’t be alarmed if your diesel mill has dark or black colored oil, but be wary of sludge buildup. Whether you have a gasoline or diesel engine, an easy way to check for sludge buildup is to look under the oil cap. Locate the oil filler cap, turn it counterclockwise and lift it off the valve cover. Turn it over and check the back. If you find lumps of oily sludge, the oil should be changed as soon as possible. However, if you only find liquid stuff, you’re probably in the wrong.

And even if your engine still runs despite the frothy oil, it won’t run for long. Running the engine constantly will cause even more problems, due to excessive friction, heat and a general lack of quality lubrication. We’re talking bearings, piston rings, cylinder wear or a clogged catalytic converter – the whole shebang. Plus, repairing them all costs a lot of money, so if the oil in your engine has changed from dark brown to frothy white, consult your mechanic immediately.

On the other hand, bluish oil also indicates pollution, as some coolants contain blue dyes that give them a bright blue hue. It could also mean a leaking head gasket, but other problems, such as a bad engine oil cooler or a cracked cylinder head, can also cause coolant to seep into places where it shouldn’t.

And then we come to greenish oil. Believe it or not, some oils are purposely colored green, so don’t be alarmed if your engine has green oil from the start. However, you may be waiting for expensive repairs if your oil has turned green instead of amber or dark brown, as this could also indicate cooling system problems such as a failed head gasket or other internal problems.

In an ideal scenario, the oil should darken enough just in time for your next scheduled oil change. The point is to be wary of sudden color changes in the engine oil, and you should get into the habit of opening the hood and checking the oil dipstick regularly to check the condition and color of the oil.

Maintaining regular maintenance, inspections and oil changes will prevent the oil from becoming excessively dark and keep your vehicle roadworthy. If you are a DIY car owner, do your best not to put the wrong oil in your car’s engine and always use the prescribed oil viscosity according to the vehicle manufacturer. If you’re unsure which oil to use, consulting your owner’s manual or a repair guide can shed light on the best fluid for your engine.