Why oil sometimes doesn't fully "wet" dipstick?

[uart]

What causes oil to sometimes “wet” the dipstick fully and otherwise not so fully.

What I mean is that sometimes when I check a dipstick the oil’s basically made a uniform coverage giving a really clear demarcation of where the oil level is.

But other times when I’ve checked it’s formed more like a motley pattern, where you can still make out the highest level but it’s not as clear cut. It’s as if the oil hasn’t stuck to it uniformly below the level. Like there are patches where the oil just didn’t stick to the dipstick.

To tell the truth I’ve never paid any systematic attention to the issue to determine if it’s due to old oil versus new oil or warm oil versus cold oil or whatever. But it’s just something I’ve noticed, Does anyone know what causes this?

 

[Summerwind]

I've experienced that as well, I sometimes wonder if it depends upon whether or not you pull the dipstick out completely straight vs putting some lateral pressure on it, and rubbing it along the inner surface of the tube, thus "disturbing" the uniforn oil pattern??

 

[uart]

Ok I'm glad I'm not the only one that's noticed it.

I'm wondering if it's in any way related to the condition or effectiveness of the oil.

 

[Summerwind]

Originally Posted By: uart
Ok I'm glad I'm not the only one that's noticed it.

I'm wondering if it's in any way related to the condition or effectiveness of the oil.


I wouldn't think so, I have noticed it on one of my cars shortly after an oil change, and with several thousand miles on it.

 

[demarpaint]

Common event for me.

 

[uart]

Now that I think about it I probably see it more often with relatively new oil.

 

[ronrackley]

The cure: "rough up" the dipstick with fine grit sandpaper to what looks like a matte finish. Just be sure to clean it well before putting it back in.

 

[demarpaint]

Originally Posted By: ronrackley
The cure: "rough up" the dipstick with fine grit sandpaper to what looks like a matte finish. Just be sure to clean it well before putting it back in.


Good point Ron! I was thinking that maybe just a good cleaning once in a while with brake clean might help. When I think about it I notice it more in my older high mile Aerostar than I do in the newer Jeep, or lower mile E-150. Next time I check the oil in the Aerostar I'm going to try brake clean on the dipstick and see if that does anything.

 

[MoparDak05]

I've noticed this whenever my oil is still hot or at least fairly warm. The colder it is the more accurate it is. Now I usually wait a couple hours before checking it. I get a clean cut line every time.

 

[Turk]

Surface tension, you need surface tension.

 

[The_Eric]

Its from oil getting on the inside of the dipstick tube from when you run it and the dipstick being pressed against it. Checking the oil right away means that the oil on inside of the tube hasn't oozed back down to the pan yet and you'll likely get some smeared on the dipstick. A trick is to look at the other side of the dipstick and typically you'll find a clear line.

 

[40Deluxe]

+1

 

[LargeCarManX2]

Originally Posted By: MoparDak05
I've noticed this whenever my oil is still hot or at least fairly warm. The colder it is the more accurate it is. Now I usually wait a couple hours before checking it. I get a clean cut line every time.


BINGO...your the Winner!

 

[hate2work]

It's worse with certain cars than with others. The daughter's Civic never seems to present this problem, hot or cold, but it's a real short dipstick and goes straight down.

OTOH, my Tacoma is terrible about this when hot. When cold, it's not a problem at all. I also used a center-punch to put a series of dimples in my metal dipstick in order to see the level easier.

 

[Tom NJ]

Common problem. Cold oil gives a cleaner line, or look on the opposite side when warm. I have found that wiping the stick very very dry with a paper towel will also give a cleaner line when hot.

I like the idea of roughing up the surface with sandpaper - think I'll give that a try.

Tom NJ

 

[ahoier]

exactly. I've only seen this in cars when I checked the oil "hot"....but also noticed it on my sister's Nissan Altime (97 I believe....), and my brother's Pontiac Sunfire (98 I think)....when I would check the stick almost "immediately" after turning the engine off.

Which is why they say you should check the dipstick "cold" (not driven for more than a couple hours, or overnight even), or wait about 5+ minutes before checking the oil level.

Cause yea, that's basically what it is, the oil is "splashed" all over the dipstick and hasn't drained down to the pan yet, and it's all over the tube, so your getting the oil that's splattered on the side of the tube.


Though I do like the sandpaper suggestion, giving a little "grip" to the oil so it stays on the dipstick better

 

[Errtt]

Originally Posted By: LargeCarManX2
Originally Posted By: MoparDak05
I've noticed this whenever my oil is still hot or at least fairly warm. The colder it is the more accurate it is. Now I usually wait a couple hours before checking it. I get a clean cut line every time.


BINGO...your the Winner!


When I worked in the large diesel arena, some of those engines we checked the level while running (for those with a dipstick) and it was difficult at times to get a level reading on the stick. I used to pull the stick (hot), wipe it off clean, cool it in front of a fan, re-insert, pull to check. Cooling the stick made it much easier to achieve a more pronounced level reading. If a fan wasn't nearby, I'd pace around by the engine swatting the stick around like flies needed a spanking to cool the stick. Others caught on what I was doing. Funny sometimes watching them acting like a nut with a play sword. Hot oil on a cool stick made it easier.

 

[electrolover]

man i hate when that happens
and its even worse when i just changed it and have get it in the sunlight a certain way to even see the oil at all

i like the sand paper idea