Oil dipstick question for 4.5 owners, which way around?

[void7910]

I seem to be getting different oil readings on the front and back of the dipstick. If the hashmarked section is facing the stern the oil reads within bounds, if the hashmarked section is facing the bow it reads high. Just finished an oil change and not sure which one to trust.

 

[Scott06]

I seem to be getting different oil readings on the front and back of the dipstick. If the hashmarked section is facing the stern the oil reads within bounds, if the hashmarked section is facing the bow it reads high. Just finished an oil change and not sure which one to trust.

how different are they - 1/4-3/8" ? You are probably getting some from the side of the tube when taking it. It doesnt have to be exact. My 5.0 I believe takes 5.5 qts after qc I never put in more than 4.5 qts .

 

[void7910]

Quite different. The side facing the bow always seems to read way way way overfilled. Maybe +1-2" on the dipstick

I am also finding the manual's spec of 4.25L doesn't seem to be accurate. It was reading right on full before the oil change and I sucked out ~4.7L. At 4.25L replaced yesterday it was still quite low. Filled to about 4.7-4.8L and the dipstick side facing the stern reads just under full and the side facing the bow reads at least an inch above.

Not sure why the stick is so different on the front vs back and why I am 500ml over spec.

 

[Scott06]

Quite different. The side facing the bow always seems to read way way way overfilled. Maybe +1-2" on the dipstick

I am also finding the manual's spec of 4.25L doesn't seem to be accurate. It was reading right on full before the oil change and I sucked out ~4.7L. At 4.25L replaced yesterday it was still quite low. Filled to about 4.7-4.8L and the dipstick side facing the stern reads just under full and the side facing the bow reads at least an inch above.

Not sure why the stick is so different on the front vs back and why I am 500ml over spec.

if it is an 1-2" higher you are just getting oil off the side of the tube. and I would use the lower side for level.

as for being 500ml or about 1/2 a qt over spec. when sucking out of a marine engine you never get all of it out. As I mentioned I add 4 qts after oil change and top up from there. Don't over think it.

Of course you can raise or lower the front of the trailer to get it exactly on the line...this has some affect on where it lands ...

if you are 500ml over or under you will have no issues with the engine.

 

[void7910]

if you are 500ml over or under you will have no issues with the engine.

Good to know. I have always tried to err on the side of caution when filling anyway but the large bold warnings in the mercury manual had me spooked about the slightest overfill.

 

[Grub54891]

I get that on some, What I do is pull the stick up a couple inches and let it sit for awhile. Then check the level. The oil in the tube can settle where it needs to be, not on the side of the tube.

 

[Lou C]

The oil drain systems where you have the dipstick tube that goes to the bottom of the pan are tricky that way. It is best to leave the stick out for a few minutes to allow the level of the oil in the tube to equalize with the level in the pan. What I've found is that if the boat sits overnight and it cools off, the air above the oil level in the tube cools off & tends to draw oil up the stick so at first it reads overfills if it was actually full. If you leave the stick out for a few min it will read closer to the true level. With a hot engine the opposite sometimes occurs, it reads lower that it actually is, till you leave the stick out a few minutes, perhaps warm air above the level of the oil in the tube keeps the oil level from rising when the oil drains back into the pan.
I have found this to be so irritating I was contemplating adding a second dipstick that enters the block in the normal small block Chevrolet location, that would read more accurately because the dipstick is actually IN the oil pan. There is a plug that covers that hole (used on automotive applications) that can be removed and a conventional dipstick can be installed if you can find one that fits with the bulky marine exhaust manifolds. It can be done on the older GM small blocks, not sure if you could do it on the Merc 4.5, I doubt it because that is not used in any non marine applications.
I have seen these conventional dip sticks added to engine packages that Michigan Motorz sells with the GM small blocks, so it could be done on an older GM marine engine.

 

[silverbul]

Oil level doesn't change, if the dipstick is bent, curled, you stick it in one way and it curles back, then you stick the other way, curles forward. Different readings. JMO

 

[alldodge]

use low side for actual reading

 

[Fun Times]

For what this is worth, the following is from two different older engine model Mercruiser owner’s manuals...(Big block 8.1L and Small block 5.7L).
Checking oil level:

Maintenance​

Checking​

1. Stop the engine. Allow approximately 5 minutes for the oil to drain into the oil pan. The boat must be at rest in the water.
2. Remove the dipstick. Wipe clean and reinstall fully into the dipstick tube. Wait 60 seconds to allow trapped air to vent.
NOTE: Ensure that dipstick is installed with oil level indication marks facing the rear of the engine (flywheel end).
IMPORTANT: Add the specified engine oil to bring the level up to, but not over, the full or OK range mark on the dipstick.
3. Remove the dipstick and observe the oil level. Oil level must be between full or OK range and add. Reinstall dipstick into dipstick tube.

Filling:​

IMPORTANT: Do not overfill the engine with oil.
IMPORTANT: Always use the dipstick to determine the exact quantity of oil or fluid required.
1. Remove oil fill cap.
IMPORTANT: Add the specified engine oil to bring the level up to, but not over, the full or OK range mark on the dipstick.
2. Add the specified engine oil to bring the level up to, but not over, the full or OK range mark on the dipstick. Recheck oil level.
3. Replace the fill cap.

Am sort of surprised the 4.5L owner's manual reads differently than many of the others in the past as it's always been mentioned that it's best to get a more accurate reading level while the boat is in the water at rest on a calm day.

Five Years Or 500 Hours; Engine Oil; Checking; Oil Level-Overfilled - Mercury 6.2L MPI Manual [Page 52]

Mercury 6.2L MPI Manual Online: five years or 500 hours, Engine Oil, Checking, Oil Level-Overfilled, Filling. • Replace The Antifreeze—Replace The Antifreeze Every Two Years If Not Using Extended Life Antifreeze—Dealer Item Engine Oil Checking Discharge Of Oil, Coolant, Or Other...

www.manualslib.com

 

[Lou C]

Interesting point about the measurement marks supposed to be facing the rear toward the flywheel. Looking at the parts diagram for the newer Merc 4.5 they changed the design of the tube; instead of attaching to the outside of the pan it goes into the the pan more like an automotive design. I bet that gives more consistently accurate readings.

 

[void7910]

NOTE: Ensure that dipstick is installed with oil level indication marks facing the rear of the engine (flywheel end).

Five Years Or 500 Hours; Engine Oil; Checking; Oil Level-Overfilled - Mercury 6.2L MPI Manual [Page 52]

Mercury 6.2L MPI Manual Online: five years or 500 hours, Engine Oil, Checking, Oil Level-Overfilled, Filling. • Replace The Antifreeze—Replace The Antifreeze Every Two Years If Not Using Extended Life Antifreeze—Dealer Item Engine Oil Checking Discharge Of Oil, Coolant, Or Other...

www.manualslib.com

Great find. Thank you for this and thanks all for the input.