Kia Optima Engine w/Sludge

I have a 2012 Kia Optima with 73K+ miles. I was having an issue with the engine light flickering on and off. I was told by the dealership that this is because of sludge build up in the engine. How much should it normally cost to repair this?

“How much should it normally cost to repair this?”

$thousands. Do you have receipts for all your oil changes? Are you the original owner?

Have you ever changed the oil? Define “engine light”.

Is it the “engine light” (presumably the CEL), or is it the oil pressure warning light that is flickering on and off?

My assumption is that it’s the oil light flickering. Sludge is all inclusive and it usually means the engine’s remaining life is going to be short; maybe very short.

Sludge is caused in most cases by oil change intervals that have too much of an interval… :frowning:

“Sludge is caused in most cases by oil change intervals that have too much of an interval.”


Or, perhaps the OP’s engine was supposed to receive synthetic oil and instead somebody cheaped-out with conventional oil. But–either way–for enough sludge to have formed so that it has led to oil pressure problems, somebody ignored at least some part of the mfr’s maintenance requirements.

What can the OP tell us regarding…
exactly how the car was maintained…
whether he/she is the original owner of this ailing car?

It would be nice to know what the dealer service department suggested as a repair.

If they suggested an engine flush to cure the problem, I’d want a second opinion.

THey may just be fishing for work and the oil was just low that set off the light.


There are additives in the parts stores for removing engine sludge. If the car were mine, I’d try one… perhaps even run a few repeated “cleaning cycles”, and see if it helps. You might get lucky. Everyone suggests “Seafoam”, but I’ve never used a desludger (I made that word up for the occasion) so I cannot speak from experience on this.

I had the same thoughts about the sludge being caused by neglect. If that’s true, simply stop neglecting your engine. Monitor your oil level, add some when you need to, and change it when you should.

“Sludge is caused in most cases by oil change intervals that have too much of an interval.”


I have never had sludge in any of my engines and I’ve owned just about every car and truck make out there. I’m a fanatic when it comes to changing oil at the proper interval.

at a dealer it will cost thousands. independent shop, it depends on the mechanic. it will require the engine to be completely taken apart, cleaned, oil drained, pan cleaned, new oil, new filter. I am OCD about changing my oil, wonder if its ever been changed on the OPs car. sludge doesnt just form for no reason out of nowhere. it takes a while

Is the OP going to return to answer our questions???

“Is the OP going to return to answer our questions???”

I guess but not doing so, we assume the sludge is due to neglect and probably not covered by Kia’s warranty.

Damage caused by negligence is never covered by warranty–nor should it be–and almost all cases of sludge build-up are caused by owner negligence.

It’s possible the sludge problem can be resolved without much expense, without disassembling the engine. I wouldn’t assume the worse without knowing exactly what light is coming on, and what computer codes have been posted to the computer’s memory. It could for example be a variable valve timing code, indicative of oil sludging only in the upper engine camshaft area.

As mentioned above, going forward OP should make sure to follow the car’s owners manual for oil/filter change intervals and make sure to choose only from among the set of oil brands and specs recommended. It’s best to choose one brand/spec of oil, and stick with it for thelife of the car. Sometimes there can be undesirable interactions between the oil additives when switching brands.