Kind of an embarrassing first post, but I have searched everywhere and haven't found a definitive answer for the problem I've been having, so I wanted to see if anyone had an opinion.

It was about a week ago, and in what I can only say was a complete mental lapse, I misread my dip stick on my 2005 Monte Carlo and added an extra quart of oil to it while it was actually slightly full already. I only encountered a problem a day later when I went on one of the main roads which was a bit faster than my normal commute, which my car began to surge and lose power while I was on the road. I didn't have any smoke or oil coming out of the exhaust or engine during this.

I then realized my mistake as I connected the two and during further research, I found that my oil must have been being whipped up into foam due to the high level. I did a partial oil change and put in some fresh oil in the car to replace the amount that I had drained too much of, getting it back to the correct level. I noticed in the oil that I had drained that bubbles were floating to the top as it was sitting in the pan, but I'm not sure if it was from the aftermath.

I tried running the car again after cleaning my PCV, cleaning/replacing some of the fuses, and disconnecting the battery (which was suppose to reset the PCM), but it didn't improve or hurt the situation. My car would have no trouble starting, but as soon as it was warm, I would start hearing knocking in short intervals every so often as it would run (I isolated the knock to the right of the belt and under the PCV valve). After getting to the normal idle temperature, every so often it will have a tiny oil pressure drop (not even a full notch usually) and then the engine will sputter and surge to about 1500-1900 RPMs making the oil pressure shoot up in response. It has gotten slightly worse after testing the past couple of days in which the car will rarely stall at idle from it now.

On the road testing from 35-40 MPH, the car will still lose power under acceleration but will be fine if I hold it steady. I did get it into overdrive one time (I know it was probably a dumb decision), but a second into overdrive the car loses power and drops out of it.

I've been getting answers like a blown gasket, stuck valves, and vacuum leaks. It's very disheartening as a novice mechanic to hear that you might've just ruined your engine, especially from just a simple lack of thinking, so I was hoping actually explaining my exact situation would help me figure out what I could do next and hopefully get opinions or try something I've overlooked.

 

No man, an extra quart wont cause anything bad.. It may be showing an underlying problem however..

I know someone who used to overfill their oil constantly.. They had an oil leak and would just dump it in there without even checking.. The couple times I checked it, it was more than twice higher than the hash marks.. This was in a 4 cylinder tempo but nonetheless there was no problems..

I guess I could totally be wrong here but I myself have overfilled at least a quart
in another car I had and didnt even drain it.. Ran just fine..

 

No disrespect wht02monte, but it does sound to me like the overfilling may have done some damage. Wasd65 did say "at least a quart". If the oil is overfilled to the point where the rotating crankshaft comes in contact with oil, the crankshaft will aerate the oil to a point where it loses viscosity. When oil is aerated the oil pump can't pump oil throughout the engine so the engine is starved of oil and the oil pressure falls off. Some engines are more sensitive than others to overfilling. I'm surprised you don't have a check engine light from knock sensors being activated. I suggest you get checked for codes, then maybe have a shop check it out.

 

^^^ Thats why I always leave room to be corrected.. Sucks nonetheless..

 

His CEL is probably burned out. Mine is. Makes me sort of not want to know about the history of my car....

 

LOL...Out of sight, out of mind right?
Unfortunately, those things tend to catch up with you.

 

Okay, through a bit of trial and error, it was recommended to just go ahead and completely replace my oil instead of just a partial change like what I did considering I might've airated my oil beyond function. I ended up doing a full oil change including the filter after adding a bottle of Motor Medic Motor Flush and running for 5 minutes like instructed. I had a hunch that the knock/click that I was hearing in conjunction with the rough idle and lack of power was possibly sticky lifters, and the click was greatly reduced while I was running the Oil Flush, so I'm still thinking that is the case.

After draining the oil and swapping the filter, I filled up using some Marvel Mystery Oil and another oil additive that was similar to Royal Purple, but I can't remember the name at the moment. I replaced 20% of the oil with both of the additives totaling about a quart in total.

After finishing up I had a moment of victory as my engine started flawlessly and with only a rare click noted every minute or so instead of constantly like before. I decided to take my car on a short field trip to test the effectiveness and driving through town was now completely returned to normal. I took the interstate on the way back and my success was dashed when during acceleration from the stoplight to 60 mph, my engine momentarily hesitated/lost power nearer the higher RPM range around 4000+ as far as I remember.

It persisted during any high acceleration on the way home. I pulled in the driveway and let the engine idle as I inspected the engine for any leaks or broken bits. From the time I got home the constant clicking is back. It returned to rough idling and surging in a minute or so cycle of losing power and then shooting up to 2000 RPMs for about 10 minutes before finally stalling. Just like before the oil change.

So after the fact, it does say for the motor flush that it might take more than one application to fully work, but instead of wasting more oil than I already have, I'm going to go on some more recommendations such as going through my spark plugs/wires and directly cleaning my lifters with lifter/brake cleaner.

All in all I'm not sure why, if it was lifters, would the problem return full force after such a short time after seeming all clear. I still have a few more things I can try, so I'll be doing those before admitting defeat.

 

Bummer!

Thanks for the update.

How did the oil look when you changed it? Any metal fragments? Did it smell burned? Look really black?

In general, aerated oil causes the most damage to hydraulic systems like adjusters, lifters, journal bearings, and especially rod bearings.

Hopefully everything will be OK, but if it comes to a major repair you might consider replacing the whole motor with a used one over repairing the valve train. There might be more damage than you can hear leaving other parts compromised. 3800 series 2 are plentiful in junk yards and you can probably get one with around 100K on it for about $500.

 

I didn't take too much note of the oil the second time that I checked because I used the oil cleaner, but the first time I noticed a few greyish fragments that drained out during the partial oil change. I'm not sure if it was metal but it seemed like just some kind of deposits possibly. The oil seemed pretty dark brown (it had a few hundred miles on it) but I'm not sure if it was uncharacteristicly dark. It didn't have a noticeable smell, but even after the oil change it did it smelled like burned oil inside the car during some of the acceleration stutters at high RPMs.

 

Man that is an ugly situation for sure. I would have not thought a quart over would have done anything to damage an engines internals. I see the logic behind Plumbobs analogy, but wow, that has to blow.

I have used a product called Z-Max to quite and free up my GM's 5.7 loud sticking lifters. Worked very well for me. The directions say it will take a few hot / cold run cycles to fully work, and it did. After about 4 days of driving the sound went away. Don't know that sticking lifters is your problem though.