I have been reading a lot of posts here related to oil color. The general conclusion is oil color did not have anything to do with how well or how clean your oil or engine is. I just ran across something interesting the other day. I just got my oil change couple day ago and when I checked my oil, it is very nice and clean and had a light brown color on the dipstick. It looks just like the oil in the GTX bottle before I poured it in the engine. This weekend, I decided to do an Auto-rx cleaning on the car and I put in 10ozs of Auto-rx in the engine. The next day after I drove the car a little bit and then checked the oil to make sure it is not overfill. The oil looks pretty black and I remenbered when I was pouring the Auto-rx into the engine.,the color of the arx cleaner coming out of the bottle is black. So I decided to take a look at what arx will affect the oil color. Here is what I did. I took 2 quarts of Castrol GTX 5W30 dino oil and pour 2ozs of arx in one of them to simulate when I just put into my engine (10ozs for a 5 quarts capacity) and then shake the bottle to mix it up and here is the result. The GTX bottle with the 2ozs of arx became so dark/black that you can no longer see through it under any light. I took a picture of it with them side by side but I don't know how to post it with this message (Can someone show me how to post a picture here?). I found that very interesting since at the end of an arx cleaning, the oil almost always look black when you drain it out, but if you look at the picture, the new oil became black the moment that I pour the arx into the new GTX bottle. That tells me I wouldn't know how clean my engine is until after the rinsing cycle is completed. You can't tell by looking at the oil color to determine how clean your engine is.
