In checking the oil today, I noticed a label that warned against pulling the dip stick out while adding oil. This struck me as odd. There must be a reason for the warning. Is it:

• The oil will wick out the dip stick channel as you add oil.
• Nobody has the manual dexterity to add oil and read the level at the same time. So don't do the impossible.
• An open dip stick channel prevents a vacuum from forming as the new oil is added. Without this vacuum, the oil is trapped overhead rather than going into the sump.

As you can see, I have no idea what the purpose is.

Comments anyone?

 

I will have to check, only warning I ever saw was don't remove dipstick while engine is running

 

It has been my experience that the dipstick reading can be inaccurate if taken as oil is being added. That was what I experienced back in the middle of the 1900s, and I would suspect that may still be true.

One reason the reading can be inaccurate while oil is being added is that the oil does not go straight into the crankcase. If you use a flashlight and look into the opening where oil is added, you aill see metal parts inside. The oil has to run around those parts, and gradually drain into the crankcase before it will register on the dipstick. Most will reach the crankcase fairly quickly, but it will take a few minutes to get some of the oil down.

We absolutely do not want to ever have the oil level very far above the full mark. Overfilling by too much can result in the oil level rising above the bottom of moving engine parts, which will then churn the oil into foam, which does not work in the injectors lubricating key engine parts.

 

I have not seen the warning and up until a couple of weeks ago I would not have understood it. The last time I changed oil in my Murano I removed the dipstick before I added the oil. I have a tight fitting plastic funnel that screws into the opening where you add oil. If I had been adding oil one quart at a time I prbably would not have any problems but I had a five quart container of 5W30 Mobil 1 that I was using. I added the oil as fast as it would drain out the funnel and thought nothing of it as I have changed the oil in the Murano and the Max a gazillion times. After replacing the oil cap I went under the car to remove my cardboard pad and pick up my tools and stuff and I noticed clean oil running down onto the cardboard. Tracking down the source of the oil it was from the dipstick tube. Seems I added oil fast and the air the the engine was venting out the dipstick tube until the oil got to the bottom of the tube and then oil was forced out. The moral of the story is to add oil slowly or to leave the dipstick in.

 

Nissans dipstick warning has been on their cars for years now. It will spit out of the dipstick tube while filling. Theres no point in taking it out while filling, just fill it to the correct amount and slam the hood