Dirty oil, but clean dipstick.

   / Dirty oil, but clean dipstick. #1  

shock

Bronze Member
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Jan 2, 2011
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91
Tractor
Ford 2910
I have a question I haven't been able to find the answer to. I have a 2009 JD 4520 Compact utility tractor. I changed the oil around 40 hours ago. Here's the question: When I check the oil, the dipstick shows clean oil on it. I expected it to be black, but it never is. Last week I actually drained a little of the oil as it was reading a touch high on the dipstick since when I changed it, and it was as black as coal, but the oil on the dipstick is still clear and yellow. What's going on?
 
   / Dirty oil, but clean dipstick. #2  
I have 2 diesel tractors, one the oil stays clean for at least 50 hours, the other is coal black in 10 hours. It's been that way since day one, both are 15+ years old.
 
   / Dirty oil, but clean dipstick.
  • Thread Starter
#3  
What interesting is the oil from the pan is coal black when I drained a little, but dipstick is clear.
 
   / Dirty oil, but clean dipstick. #4  
My first thought is whether you're sure you're checking the right dipstick. Yeah, sounds dumb and I'm sure you know what you're doing, but my tractor has a bunch of dipsticks so I can imagine a scenario where that could maybe happen. Otherwise the dipstick should have the same oil on it as what comes out of the pan because it's literally coming from exact the same place. Only other thing I could think of is that a thin layer of oil on a dipstick can often look a lot cleaner than half a quart of the same oil dumped in a pan.
 
   / Dirty oil, but clean dipstick.
  • Thread Starter
#5  
Yeah, I expected someone to mention this :) But, yes, I'm sure it's the right dipstick.
I'll wipe it off on a paper towel next time as 1/2" of oil can look different than a small amount on a dipstick. Still, before the oil change, the oil on the dipstick was visibly dark, and today, it's not...Thanks for the response.
 
   / Dirty oil, but clean dipstick. #6  
Take some of the dark oil you take out, and dip the dip stick into it. I’m guessing it will look clear on the dip stick.

Just a guess, but I think a thin film, just doesn’t look as dark, as a sample which is deeper, and the light traveling through it just looks darker than a thin film.
 
   / Dirty oil, but clean dipstick.
  • Thread Starter
#7  
Good advice - Thank you !
 
   / Dirty oil, but clean dipstick. #8  
Also, wipe the dipstick on a white paper towel. You'll see how clear it is pretty quickly.
 
   / Dirty oil, but clean dipstick. #9  
If you drained cold oil from the drain plug hole, you’re removing some of the settled soot/contaminants which would be darker than the oil higher up in the pan…
 
   / Dirty oil, but clean dipstick. #10  
When you drained some of the oil did it change the dipstick reading?
 

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