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Too much oil in car

2010 ford mustang convertible 4.0 V6 10 K plus miles

oil changed 200 miles ago by dealer, checked oil and it was overfilled, receipt states 6 quarts instead of 5, changed oil and filter again. Now at correct level. Went through older oil change receipts. Receipt for oil change at approximately 3k miles states six quarts. It looks like I drove 3k plus miles with an extra quart of oil in the engine.

What should I check for damage or premature wear?


The extra quart probably won’t mean much. It’s if the oil level in the oil pan reaches a level where the spinning crankshaft contacts the oil it can cause the oil to foam. And if that happens you lose oil pressure. If you drove the vehicle with no oil pressure problems, that extra quart didn’t raise the oil to that level.


Thanks. It’s a base model so I don’t have an oil pressure gauge (wish I did). But I did not notice anything. Maybe an oil smell at some point, hard to tell … it was summer… top down radio up, trucks on the highway smell. From what I’ve read the car has a fairly large oil pan. The oil level was above the upper of the two holes. I should try to figure out how much over max that put me.

I was just wondering if there was an un-bozo check list. This seems to happen enough… Many mustang forums tell this tale.
Thanks again.

You should be fine at only a quart over. My daughter has an '05 with the 4.0 and I’ve noticed the last few times I’ve changed the oil that putting a 5 quart jug in there seems to be leaving the oil level about 1/3 of a quart down. (After the oil filter is filled.)

On the next go around I’m going to start measuring what comes out of that jug just in case some bean counter has decided to increase profitability by shorting the jug a bit.
In this case it’s happened twice in a row so the curiosity factor has gone up.

I would not be surprised that an oil change with a filter change takes just over 5 quarts and they are billing you or the manufacturer for 6 quarts.  I'd bet the book says it takes 6 quarts for anything that needs over five.  The oil may come out of a 55 gallon drum and they bill you for the full quart even if it needed an oz over five.

You were fine at 1 quart over. If you’d had a problem it would have been foaming of the oil, and you’d have experienced symptoms of oil starvation of the bearings…which you haven’t or you’d be posting about loud knocking sounds.

Sleep soundly. You’re fine. Kudos for checking the oil level.

That could be but… in the course of three oil changes they billed me for 6 quarts, 5 quarts, the 6 quarts respectively. This last oil change did overfill the car’s oil level so I am inclined to believe the first oil change also did.

The dealer does not make that much on the oil changes so I would believe there is pressure on the technician (may just an oil changer) to move as quickly as possible.

My understanding is they enter the number of quarts into the oil pump. An overworked person and a 6 instead of a 5.

Interesting point. The car has been sitting in the garage since last night. I will check the oil level later today and see where it finally settled. I will let you know.

Knocking… I listened to the motor (hood open) and I was surprised how much of the mechanical sounds in the top of the motor I could hear. This could be because the motor is fairly quiet compared to say my quad cab pickup with the V8.

However having a mechanic listen to the motor outside the shop with a lower ambient noise level could not hurt.

It never hurts to consult a mechaniic, but the knocking I’m referring to (bearing knock) would be obvious from even inside the cab. It’s a very loud and scary sound.

Funny story. Friend at work told his son to check and add fluid at every fillup. He did not check it, he just added a quart. His dad got a call, “I’m at the gas station and the car won’t start”. Just for grins dad pulled the dipstick, before looking at anything else and it was to the top. Drained and refilled and all was fine.

FYI just checked the oil level… below the top hole (which is a good thing). Although it looks like more than 2/3 of the way up from the bottom hole. Maybe they lose less oil since their filler hose was already primed. Perhaps you get more out when you drain it. I’m not sure how warm my engine was when they drained it or how long they waited. Perhaps bean counters…

Well after complaining to Ford about the oil overfilling Ford stepped up to the plate and gave me an extended warrantee for free. I was impressed. However, Just had my oil changed by a local dealer this morning (they knew of my previous overfilling problem) checked my dipstick and receipts tonight overfilled by a quart. Oh well…

Don’t be too alarmed by some top end noise. The fuel injectors firing make a surprisingly loud racket. If there’s no clicking on a fuel injected motor, I’d be worried…of course, it probably wouldn’t be running, either.

Must have been about 1968 when my future FIL bought my future wife a '62 Dodge to use at school with instructions to fill it with oil. She drove it 90 miles home with smoke billowing all over the place. When questioned she said she filled it up with oil, completely filled it up to the top. It was fine though after draining about ten quarts of oil. Needless to say, I’m the one that does the oil checking around here.

Many times, excess oil will be extracted by the PCV system and you will find it in the air-cleaner box…You might check that…

Next time you change your oil tell the Ford dealer you will only pay for 5 quarts, if they put in 6 the last quart is on them and you won’t pay for it. Then buy a quart of equivalent oil and check the oil level the next morning and top off as needed. Running the oil level at 2/3 to 3/4 between the low and fill mark should be fine. Anything about 1/2 between the marks is fine with me, I only top off when it is below the 1/2 area and then just enough to move it up to about 2/3 to 3/4 of the full mark.

I just wanted to add that top end noises in modern overhead cam engines are normal. The pad under the hood is there to quiet the noises from outside the vehicle and most engines now have plastic covers over the tops of the valvecovers with a noise dampening material underneath. Usually it’s a sprayed on firm foamy type of stuff, much like the expanding foam insulation you spay into cavities in a house.

A quart over is harmless, but anywhere between the top notch and the bottom notch with the engine off is proper fill. Exactly where it’ll be will depend on when you check your oil. Shut the engine off and check it and it’ll generally be lower than if you check it in the morning. It takes a while for all the oil to run down from the top end. That’s why if you change your own oil it seems to take forever for that thin strand of oil running down into the pan to stop, and it’ll drip even longer.