Must wipe dipstick when checking oil?

When the engine is cold, I just pull it out and look. If it has been running, I wipe it off and dip it first. This has worked for me for the last 20+ years...

 

I pop the hood in the morning before I crank it, been sitting for about 10 hours, Why and how could that reading be wrong? It's about as right as could possibly be. See no need to wipe, guess I'm one of the skidmark people.

The time to wipe a dipstick is when it's been running recently, then the splashed oil might give a false reading. If the engine is shut off and the reading taken right away, some of the oil won't be back down in the sump yet. But it will give a rough idea, and also can be checked for milky oil (meaning a coolant leak).

 

If the dip stick has a really good Tight seal you can get a “ syringe affect” when you yank it out pulling oil up the dip stick tube giving a false reading.

 

I've had it the other way too where it'll actually come out dry or very low.

 

Some different Cats including some A and B models came with a long internal dipstick tube that allowed oil to be checked running, two sets of marks on the stick. This was a holdover from stationary and equipment engines from the 50's and 60's. This was a time that the engines may be run for days on end and needed to be checked at least daily.

 

Maybe it was actually low but after yanking it out a few times you were staring to pull oil up the tube making it read higher?

 

I thank your and @AModelCat ‘s replie on that. I knew about the stationary Cats and Detroits doing this from the days of my youth hanging out with my dad on drilling rigs and watching some of the old timers actually changing the oil and filters with them still running. I did not know the old truck engines did that on the sticks too. I’ve always been around Cummins when it came to trucks and as far as I know they didn’t do that. Thanks again for the learnin’.

 

My 3406B model CAT has a mark for engine off cold on one side. Engine running warm on the other side.

 

Wife always telling me I'm to picky so I just wait till the red light comes on lol.

 

Same with locomotives. Can't shut them down in winter because their coolant doesn't have anti-freeze. I'd love to have two marks on my Cummins stick.