Hey Guys,

I have an RX300 and enjoy doing a lot of my own maintenance. I've been using Mobil1 and changing the oil every 5k miles or so. After a short trip of traveling about 100 miles, I randomly checked the engine oil and the levels on my dip stick were really high. I measured it a few times and the engine oil levels on the dip stick were probably 2x or 3x as higher than the normal "range" on the dipstick. I don't remember if my engine was running or not. This may be way it was soo high. Few questions here:

1) Aren't you suppose to measure the engine oil levels when the car is warm? Measure when the car is warm and engine off?

2) What are the consequences if any for filling up your engine with too much engine oil. My understanding is that the engine oil capacity is about 4.7quarts. When I perform my oil change, sometimes not all 4.7 quarts are emptied so I'm afraid over time, I might have "overfilled" my engine. Is there any apparent danger?

 

no real bad consequences...

1) can cut down on gas mileage and power due to the crank splashing through the oil too much...

2) can cause excessive crankcase pressure (due to atomization of the oil that was splashing in #1) which can lead to some small oil leaks...


Neither are hugely detrimental...

Oil level should be checked after the engine has been off for a few minutes to allow the oil that sometimes stays up in the head to drain down... the fill capacity is only a guideline, go by the dipstick, so long as it is not damaged - it will make sure you have the correct amount...

 

I agree with mitsuguy.. there really arent any hugely bad effects from too much oil. However, if you run way too much, more oil can get sucked through the PCV and you will burn a lot of oil. If you're a half a quart to a quart overfilled, i wouldnt worry too much.

 

It can also shoot up the dipstick pipe and make one hell of a mess of the engine compartment.

 

What happens when an engine is overfilled with oil?

So you topped up the engine when it was warm after getting a faulty dipstick reading, or you put too much oil in when you changed it yourself. What's the worst that could happen? Well the problem with this is that the next time the engine is run, the windage in the crankcase and other pressures generated by the oil pump, etc. place a great strain on the seal on the rear main bearing.
Eventually, often much sooner than the ordinary man in the street might expect, the rear main bearing seal ruptures, and the engine becomes a 'leaker'. If you've got a manual gearbox, this means one thing: this oil goes right onto the flywheel and the face of the clutch disc. A lubricated clutch is A Bad Thing. If this still goes unnoticed, the front seal is the next to go, and the engine then becomes a 'gusher' (or to be more colourful, it starts pissing oil all over the place). As well as smothering the clutch with oil from the rear, the oil now coming from the front leak will be neatly distributed about the engine bay as it hits the front pulley - often propelling it out as far as the brake discs. At the same time as this Hollywood disaster movie is unfolding outside the engine, things aren't working out any better on the inside. As you can see from the diagram, the correct oil level is really close to the rotating crank. Overfilling will mean the crank dips into the oil and churns it into a froth. Froth is good on certain types of coffee but not good in an engine. The mixture of aerated oil will be forced into the bearings and in case you didn't know, air is not a lubricant. Typically this means that bearing damage will follow quite rapidly, especially if you are driving on a motorway. You'll know bearing damage when you get it. The engine smells like a garage mechanic cooking over an open flame and the noise coming from the engine is the sort of thing you'd normally hear in vaudeville plays when a piano is pushed down a flight of stairs. As if that all wasn't bad enough, the excess oil gets thrown up into the piston bores where the piston rings have a hard time coping with the excess oil and pressure. It gets into the combustion chamber and some of it will get out into the exhaust system unburned resulting in a nice patina of oil all over the platinum surfaces of your catalytic converter. This renders it utterly useless for good.
Well, you did ask.

 

You mentioned you changed your own oil.

If you've done this several times, and this is the only time you're getting weird readings, perhaps the dipstick or dipstick tube is somehow damaged and you are getting a false reading.

 

Perfectly normal for the crank to splash through the oil just a little... oil does not aerate anywhere like you mention... it is also perfectly normal for the oil to be atomized in the open spaces of the crankcase... on performance cars, we knife edge the crank and install a crank scraper to combat this, but it is not required nor really needed on daily driven cars... it's really a horsepower thing more than anything....

 

what does your dip stick look like? have a pic of the oil level?

 

You need to take into consideration the degree of overfilling.
If you've double-filled because you've completely forgot to drain the oil then I'd agree you're likely going to get some doom and gloom as mentioned above, and you should take some action.

If it's overfilled even a significant amount over (say an extra quart), then my advice is not to worry.
I'm sure someone will argue there's some car out there that will instantly explode if there's 1 fluid oz too much, but toyota usually has quite a bit of leeway and is not that picky.
Think of this, if the car was so sensitive to the oil level, then you'd only be able to go straight, and going uphill or downhill or accelerate or brake hard would cause doom and gloom.


I suspect you may not be taking a good reading. If you're taking a reading with the engine on or just turned off, oil might be splashing or draining all over the place, so the dipstick is just going to get oil all over.

 

Just make it simple. Read the dipstick. You can't really depend on the amount of drained oil to determine how much to put in (this is not transmission fluid and engine oil will burn), so just follow the dipstick.

 

Check it in the morning after the car cooled down over night and all the oil drained down. If you check it right after turning off the engine, it will be way off since the oil is all over the place and it splashes onto the dip stick making it read higher than normal.

 

I've over filled my engine oil to an extent to where the oil, shot up through the air intake, landing in the air intake filter and below, pouring into the engine head near the starter, underneath the car, and places that are not good.

Learned my lesson to never fill more than 6.5 quarts heh.

 

The increased pressure can cause seals/gaskets to wear prematurely and leak.

 

[QUOTE=habeeb89;4596432]The increased pressure can cause seals/gaskets to wear prematurely and leak.[/QUOTE what if I already have a timing cover leak it will just weep away with the extra pressure ?