Dipstick - The mistery of reading it

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Windwalker

The two engines I have owned over the years seemed to give me fits when attempting to read the oil level on the dipstick. Firstly, I owned both universal M-15 & M-18's. Virtually identical. So when I pull out the dipstick after filling the engine to the spec level of oil, (2.5 & 3.0 qts respectively). I then run the engine, & check the level the next day. Upon the initial pull, the oil barely registers on the dipstick (seemingly indicating too low on oil). I clean the stick off, reinsert & reads halfway up the stick (indicating too much oil). If I had to guess, I'd say the initial reading is more accurate, as after the first check I'd bet some oil follows & hangs in the dipstick tube to give any following reading a false reading. But you know I've changed oil over a dozen times (to spec) and it reads low every time. I end up leaving the engine alone & changing the oil more often since I don't feel I have a reliable way to measure the level. Ideas? Help me avoid the regular nightmares I have of seizing my engine up...
 
May 25, 2004
173
Oday 25 Tampa Bay
m-18

I have the M-18. When I check the oil, I pull the dip stick out, clean it, stick it back in, pull it out again, and take the reading. That is with a cold, level engine.
 

Dan H

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Oct 9, 2005
143
Catalina C25 SW Michigan
Trapped air?

I'm guessing that air is trapped inside the dipstick tube after you've drained the oil and re-filled the engine, the reason it reads low. Upon pulling the dipstick out the next day, the oil level runs up the tube and reads too full. I always check my oil in my vehicle, and all engines, several times, never just once. Suggest remove the dipstick while filling the engine. After filling the engine, have a cool beverage and then check the oil two or three times. Dan
 
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Ron

oil gone to fliter

When I change the oil in my Perkins 30 , I remove and dry off the stick. A change the filter and replace the recommended amout of oil. I insert the stick and get a reading. After running the engine, I check to see that the oil pressure light and alarm have gone on and off. I recheck the level again, knowing it will read low because some of the oil is now in the filter. I leave the dip stick out overnight and check it again when cold. The new oil can be hard to see on the stick. If in doubt, I mark a paper towel and lay the stick on top of it. The mark is now obvious. Hope this helps.
 
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Windwalker

oil in filter

I suppose the oil level could actually be low as the filter surely takes a fair amount of oil to fill, I assumed that space was considered when writing the spec, no? I wasn't too specific about this, but I get the same too low/high readings every time I take a reading (weeks, months later) so I doubt it is a trapped air issue. Do others get a low reading when they fill their engine oil to spec? I'm hesitant to add more. Does too much oil damage the engine?
 
R

Ron

Ron again

Too much oil is not good. Have you tried draining the oil and measuring what you get out, compared to what is specified to go back in ? Some engine manuals state the capacity with or without the oil filter.
 
G

Glenn

Initial oil reading

Your initial oil reading will be low. As you do, wipe off and take another reading. I think it was Stu Jackson said that when the engine cools, a vacuum is created sucking the oil from the dipstick tube. Reomving the dipstick lets the oil flow back into the tube. I always let the engine warm up at the dock, shut it down to check for leaks and check the oil again. Also, my engine, Universal 5424 requires 4.5 qts, but I have never been able to replace more than 3.5, can't seem to get it all out.
 
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Windwalker

Ron, Glen, Good points

I'll have a look-see at how much oil I get out. My first engine the M-15, had to have the oil sucked through the dipstick so I'd potentially not get it all out (out of 2.5 qts, I got about 2.2 out). My M-18 has an oil drain hose on the bottom of the oil pan so I "think" I'm getting it all out. I'll need to carefully measure what I get out next time. Also Glenn has a good idea, since oil follows the stick up the tube when I pull it out, I might try pulling it out just enough to release any pressure say 1/2". Thanks for all your ideas!
 
Feb 26, 2004
23,047
Catalina 34 224 Maple Bay, BC, Canada
Dipsticks on U engines

Glen Thanks for remembering me, but I was wrong back then. It's simpler. There's a seal on the dipstick. Just pull it out, give the oil a few seconds to settle and thn reinsert the dipstick and then measure it. It is NOT like a car, which usually has an open dipstick tube. Look at the dispstick itself, it has the seal on the handle! Read the manual. Stu
 
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