I changed the oil for the first time on my "new" 98 jeep. I got it at 205xxx, it's 207500 and I decided the oil color was finally starting to brown from the usual light tan. After 10 minutes of letting the oil out and running about half a quart through the engine of 10-30 syntehtic blend, I could see that the oil was really dark as compared to what I was seeing and seemed to be a bit sludgeish? Changed the filter to an KN filter. And put in engine leak stop and about 5 qts of 10-30 sb. I have checked the oil on over 500 cars and added oil to at least 100 and this was the very first time I couldn't even see where the oil was on the dipstick, I had to actually hold it at an angle to see where the oil stopped and the stick was dry. i have never seen such clear oil in my life? What could be making the sludge and how do I get more of it out if there is more in there? and is such clear oil a good thing? First time doing a start to finish oil change here... the next oil change will be 10-40..

 

Accelerating the oil change schedule a bit will help clean up the motor. Using a high detergent diesel oil (Rotella, Delo) or a good synthetic (mobil 1) will help speed the clean-up a bit.

I've noticed that too, sometimes I can't see the oil very well on the dipstick. Gotta hold it sideways and look for the liquid.
Dipstick turns a nice light tan after a while from age making it harder to see. That and recently "graduating" to bifocals...that isn't helping either