The following is general info regarding engine oil overfilling.
Surplus lubricant can get agitated by the crankshaft and other moving parts. This can only happen if the oil levels in your vehicle are too high.
Eventually, the viscous fluid will be transformed into a frothy foam, and the lightweight froth won’t be effective as a lubricant or a dispersant.
It will also contribute to inconsistent levels of oil pressure. All of these factors can provoke the following performance-related issues:
Misfires or stalling.
Trouble speeding up.
Frequent overheating (check our article on cars overheating if you experience this).
Difficulty getting the motor running.
What Happens If You Put Too Much Oil in Your Car? When Is It a Problem?
A millimeter or two over the fill line shouldn’t be anything to panic over, especially if this only happens once in a blue moon. On the other hand, several inches above the fill line is something to worry about.
A quart or more of unneeded motor oil in your car is a cause for concern.
Here’s what could happen if you keep driving with an overfilled reservoir:
Clogged Catalytic Converter
When there’s an excess amount of oil circulating, it’ll go places it shouldn’t. One such example is your catalytic converter, where it will burn.
This component wasn’t designed to handle fluids. If it ends up clogged, your motor won’t run smoothly.
After a certain point, your engine may even completely stop running.
Catalytic converters don’t come cheap, and replacing them isn’t easy.
My dealership did this on my 2015 and my wife's 2016. They continue to do it on my 2019. They put in 6 liters every oil and filter change. I force them to remove 1 liter every time. They give no reason for doing this.
THIS is the kind of garbage that keeps me doing ALL my own maintenance.
I can barely believe I'm reading this complaint. I could almost understand if it was happening at some discount kwikki-lube outfit, but the dealer!!? Grrrrrrrr.....
Grouchy old man here.
I taught high school auto tech for 28 years and this was always a problem I had with my students!!! If I wasn't standing right there watching them fill the crankcase sure enough they would overfill it. When they get out into a dealership there is no one standing there watching them. You would think they would get it after a while but they don't. This happens more so when the oil is being taken out of a 55 gallon drum and they are using a crank pump to draw the oil into a oil container. Unless they have the oil in quart containers where they can dump in the exact amount of oil the specs call for there is more of a chance for it happening. Like anything else it just takes a technician that is paying attention and proud of their work to do it right.
You just gave me a flashback to 1978.
Tucson, Arizona, Catalina High School, Auto Shop, Mr. Haynes.
Mr. Haynes allowed us to bring in our own vehicles to perform oil changes and other minor maintenance. My sister, who was 10 years older than me, had a '73 pinto wagon in need of such maintenance.
She stopped at an auto parts store and picked up the correct filter and a case of oil. She was a contingency planner, so she bought a lot of oil.
I felt like kind of a big shot, having my sis bring in her car. She was pretty hot, according to my classmates.
Everything went like clockwork til it came time to dump in the oil. I never saw my dad buy more oil than he needed, so I dumped in all 12 quarts.
When Mr. Haynes came over and inspected my work, after he checked the dipstick, he looked over his glasses at me and said,
Mr. Shetler, For this project, you have earned an F!
Was filter changed? it holds enough oil to show on dipstick; I've always thought if there was two much oil it would burn off....but never checked this out since If low oil light comes on, I park TK and wait until oil drains into crankcase, then take out dipstick and note reading. Never had this overfill problem but If it was serious I'd drain oil from crankcase.
They did this for every one of our free oil changes. I took it back once and they fixed it. After that I just drained the extra my self. The last 2 oil changes were done in my garage. Both resulted in a level about 3/4 of the way above the bottom dimple. Just like I like it.