How Adding Too Much Oil Can Be Detrimental To An Engine

[ChristianReske]

In most engines the crankshaft is several Inches away from the maximum oil level when the engine is not running.
I think it is one of the myths of the internet: "The crankshaft splashes into the oil". It is simply not possible.

 

[billt460]

.... When most engines start, the level in the oil pan drops 1 - 2+ quarts, so it would be very hard to overfill an engine to the point the crank is touching the oil when running.

On some engines it's all but impossible. I know out here there are guys running jet boats powered by big Oldsmobile V-8 engines. Some of the Olds V-8's can have a problem, if run at constant high RPM's, (like on a jet boat), they can literally suck all the oil out of the pan until the oil pump sucks wind. The oil is all up at the top of the engine, and cannot drain down fast enough.

This can starve the bearings, and the bottom end for oil, and damage the engine. There is an oil restriction kit to fix this, that somehow limits the volume of oil that can be pumped to the top end. But having those engines a quart overfilled is hardly an issue.

 

[930.engineering]

OK understood, but that article REALLY didn't address your finer points nor did directly address the fact that some clown puts three qts over max.........kinda is an idiot and shouldn't even pop the hood.

Pablo, I intended to address the forum, not the author of the article.

Show me an engine with 7.75qts written required capacity, exact center of dipstick RANGE marks, that would even come up to MAX with 0.25qt more oil (8qts) AND with those 8 qts would suffer in any way. To me, this would be a very poor design!

I agree, it's unlikely that a quarter of a quart will cause issues in this case.
However there are idiots thinking 'more is better' putting two quarts more
in an engine with just 4 or 5 quarts capacity. Don't think it doesn't happen
on this forum. Even on Bitog the 'more is better' approach is fairly popular.

Engineers design engines knowing maintenance is sloppy, so they can operate just fine over filled and underfilled by a large amount.

What's 'a large amount' and how would you determine this amount?

I've seen many engines running just fine that are 2 + quarts low on oil. When most engines start, the level in the oil pan drops 1 - 2+ quarts, so it would be very hard to overfill an engine to the point the crank is touching the oil when running.

How did you determine these 'many' engine were actually running 'just fine'?
Granted, they were still running obviously, but under which conditions of use?
At two quarts low I wouldn't (edited) guarantee for sufficient oil pressure under
hard braking or cornering. Most engines will even survive that for a couple of
seconds but that isn't what I'd call a 'safe operating condition'.

In most engines the crankshaft is several Inches away from the maximum oil level when the engine is not running.
I think it is one of the myths of the internet: "The crankshaft splashes into the oil". It is less likely on most but possible on some cars.

I fixed that for you.
This is under static conditions - when the car is at a stand still. Imagine harder braking
or cornering or both. Anything's possible, remember boxer engines (without dry sumps).
.

 

[Owen Lucas]

I've been overfilling my 2.4l 2AZ-FE in my 2005 Scion tC by 1.2 quarts for over the past 4 years (50k miles). Capacity is IIRC 3.8, possibly 4qts, I just dump the whole 5 quart jug in. No leaks, no problems that I can tell. These engines burn oil in higher mileages (190k) and though mine is not burning very much, *(maybe .5 qts after 5000 miles) I add it as insurance. I guess some engine sumps have more room for extra oil than others, maybe I'm lucky, IDK, not an engineer.

For the experts: Is 1 qt extra too much for the 2.4 liter?

 

[ChristianReske]

I fixed that for you.
This is under static conditions - when the car is at a stand still. Imagine harder braking
or cornering or both. Anything's possible, remember boxer engines (without dry sumps).
.

I dont imagine, i do. I have a Oil pan with a baffle ready to install in spring.

But I still have a hard time to imagine how oil that is pressed by G-forces in Corners or braking against the walls of the oil Pan can reach the Cranksahft some inches or centimers above the bottom of the oil pan and away the sides of the engine Block.... i have a very hard time to imagine this!

Picture:
Oil windage tray removed. Distance from Oil pan bottom - indicated by the pump strainer - to crankshaft 6 inches - 15 Centimeters, minimum!
How could the cranksahft splash into the oil?

If you look closely, you could see the oil Dispstick on the left above the pump strainer. You have to overfill the engine with several GALLONS to make the crankshaft splash into the oil.

 

[930.engineering]

.
At 1 g (9.81 m/s²) of acceleration the upper oil surface line is at 45° degree.
Again, it obviously depends on the specific engine design and conditions.
So still, as a general rule, I'd recommend to just stick with the manufacturer's
recommendation: Keep it between MIN and MAX. Keep it close to MAX if you
feel more comfortable with it. You can't go wrong with that.
My intention never was to tell you what you should do. My intention was to
be careful with general recommendations to the audience.
.

 

[ChristianReske]

Yes. I allways keep it on Max. Lelvel. Sometimes 0.2 Liters / Quarts above Maximum.
Better for a hard driven car and engine.

 

[circuitsmith]

Likely'? Is 'likely' safe enough for you?

Here we go again with the trivial semantics!

but please be careful with general recommendations on public forums.

Or what? The public will demand their money back?

I already have enough alarmists in my life.
So long folks!

 

[930.engineering]

.
If being helpful isn't your intention you'll have a hard time understanding me.
.

 

[FZ1]

I've been overfilling my 2.4l 2AZ-FE in my 2005 Scion tC by 1.2 quarts for over the past 4 years (50k miles). Capacity is IIRC 3.8, possibly 4qts, I just dump the whole 5 quart jug in. No leaks, no problems that I can tell. These engines burn oil in higher mileages (190k) and though mine is not burning very much, *(maybe .5 qts after 5000 miles) I add it as insurance. I guess some engine sumps have more room for extra oil than others, maybe I'm lucky, IDK, not an engineer.

For the experts: Is 1 qt extra too much for the 2.4 liter?

Different strokes. You could keep the 1.2 quarts in the bottle and top up as needed. Jmo

 

[Kjmack]

It depends on the engine, i guess.
My S2000 has a windage tray under the crank to avoid oil foaming, for example.
My Kawasaki ZRX 1200 engine has exactly the same Bottom end as the previous ZZR 1100 engines. Kawasaki has lowerd the oil volume and the position of the oil gauge glass on the ZRX 1200.. Many ZRX owners (me to) overfill the engine. Everyone is puzzeld why kawasaki has done this... and agin, the Bottom ends of the engines are 100% identical.

I have done the "Fill it by the volume printed in the handbook" method a few times, never worked for me. I fill engines now judging by the dipstick or oil gauge. I check the oil level allways before i start the engine, when i could be sure that all the oil hass settled in oil pan. I allways keep it near maximum level. Better save then Sorry...

What realy puzzles me: When a engine is running, the oil level in the oil pan is reduced about 80%, because the oil is sucked into the pump, splashed around in the engine and needs a little bit of time to flow back. You could see it here from Minute 7:40 around:



With so little oil left at the bottom of the oil pan when the engine is actually running, how could a little overfill do harm? I just dont understand it.

Those dude's didn't even know how much that old relic even took . Goof balls .

 

[madeej11]

Different strokes. You could keep the 1.2 quarts in the bottle and top up as needed. Jmo

Yeah I agree. No way would I dump an extra 1.2 quarts purposely in an engine. Doesn't make any sense..

 

[ChristianReske]

.
If being helpful isn't your intention you'll have a hard time understanding me.
.

You sometimes "sound" a little bit harsh when i read your Postings. Just saying, no offense.

And, in a forum like this, in a thread like this, we can not discuss every single engine and differences in construction between them in detail.
So, we just have to "Speak generally". Hoping that the reader knows the differences and do his own conclusions.

 

[ChristianReske]

Those dude's didn't even know how much that old relic even took . Goof balls .

Maybe. But, you could see how much the oil level drops when the engine runs. Thats the whole point.

 

[ZeeOSix]

On every car, truck and motorcycle I've owned, I always fill to the "Full" mark on the dipstick or sight window. Never had any issues. Typically I've found that If I put in what the manual says the level will be a little below the Full mark. When I drain the oil I let it drain much longer (and it's probably hotter too) than say a typical dealership would do. That could be a factor, and maybe manuals assume a quick drain.

I've also found that pretty much every vehicle I've owned that the dipstick is pretty accurate. If the oil level is on "Low" and I add a quart, the level ends up on the Full mark. I've always trusted the dipstick.

 

[CharBaby]

 

[930.engineering]

You sometimes "sound" a little bit harsh when i read your Postings. Just saying, no offense.

It's been harsh just because I answered to a harsh post.

And, in a forum like this, in a thread like this, we can not discuss every single engine and differences in construction between them in detail.
So, we just have to "Speak generally". Hoping that the reader knows the differences and do his own conclusions.

That's exactly why I said we should be careful with generalizations.
.

 

[cb450sc]

I remember getting a recall notice for my 2011 Kia Optima with the 2.4 engine. So that the engine wouldn't implode they put in a new dip stick and said that the engine now takes 1/2 liter more. So there was extra room available in that engine anyway.

 

[Duffyjr]

I've never seen a dipstick where the crosspatch went above the full line, there must be a reason for that

 

[Jetronic]

In most engines the crankshaft is several Inches away from the maximum oil level when the engine is not running.
I think it is one of the myths of the internet: "The crankshaft splashes into the oil". It is simply not possible.

I miscounted litre bottles once when I had a Citroen AX with TU 1.1 l engine. I added 1 litre or more over max. That crankshaft hit the oil and I knew it, shook the whole car like the engine was going to drop out, and lots of blue smoke out of the exhaust until the level dropped sufficiently.