Oil Sludge is a sticky substance that coats your engine, clogs its arteries, retains heat and destroys most of what it touches.

It's like a heart attack for your engine.

While some sludge is preventable, certain engines have a pre-disposition for this hell stew. That means entire generations of certain cars are at risk.

What the Heck is Oil Sludge?

Brand new oil is a relatively clear, free-flowing liquid that can easily make its way around the engine. Its job is to lubricate parts and reduce friction. Less friction means a cooler, happier engine.

So how does something like that turn into the tarpit known as sludge?

  1. The oil has additives that absorbs soot, dirt, water, metallic particles, excess fuel, and anything else that can gunk up your engine. It can only do this for so long, however, because oil has an absorption capacity. Once the oil passes its capacity, it starts to thicken.
  2. Over time, the heat of the engine breaks down and oxidizes the oil. That allows the molecules inside the oil to combine with all the contaminates the additives have worked so hard to collect.

Eventually, what was once a free-flowing liquid can turn into a sticky hell stew that coats the inside of the engine. Once that happens it goes from something that reduced friction to something that increases it.

More friction = more heat. More heat = oxidized oil. Oxidized oil = more friction. You can probably see where this is going.

What Sludge Looks Like

Dodge and Chrysler 2.7L Oil Sludge Dodge and Chrysler 2.7L Oil Sludge Dodge and Chrysler 2.7L Oil Sludge Dodge and Chrysler 2.7L Oil Sludge

$4,381 bucks An Expensive Fix

The average repair cost for oil sludge is over $4,000. The reason is simple -- once you're sludged, you need a whole new engine.

87,431 miles Average Breakdown

As engines get older we expect things to break. But doesn't it seem like you should at least be able to get to the century mark?

1,021 complaints (And Counting)

Oil sludge in the 2.7L Chrysler engine is one of the most often reported complaints to CarComplaints.com.

Common Causes of Oil Sludge

Once you have oil sludge, you’re doing damage to your engine with every stroke. So what are some of the ways this can happen.

Neglect

The most obvious cause of sludge is a neglectful owner. Poor oil change habits will lead to the oil oxidizing in the engine. So if an owner ignores a warning light or tries to skip an oil change, the oxidized oil “cooks” and turns gelatinous. It’s foolish and can do serious damage to your engine.

But it’s not always neglect that causes sludge. In fact, in some cases there are defects that generate sludge even in the most meticulously maintained engine.

Crankcase Ventilation System Defect

Oil sludge can be the result of a poorly designed or defective crankcase ventilation system, like the one found in the 1998–2005 DaimlerChrysler’s 2.7L engine. This engine is notorious for allowing hydrocarbons to enter the oil and break down the additives that help gather all the gunk.

Additionally, water pump gasket failures have been known to leak coolant into the oil. And all those extra contaminates can severely degrade the oil’s life.

These issues have caused an incredible amount of sludgy complaints from owners of the Concorde, Sebring, Intrepid and Stratus.

Engine Operating Temperature

Oil oxidizes the most when the engine’s operating temperature is too high. The oxidation only gets worse when that heat lasts a long time.

Volkswagen’s 1.8L turbocharged engines have a history of sludge-related complaints. From 1997-2005, their turbocharged engines came equipped with a tiny 3.7-quart oil capacity. And mechanics say it doesn’t provide the engine enough oil to dissipate the heat and it removes all margin of error for owners who may be a little late on their oil change.

Vehicles with a History of Sludge

ComplaintsMakeModelYear 
149DodgeIntrepid2001oil sludge resulting in engine failure
148DodgeIntrepid2000oil sludge resulting in engine failure
141DodgeIntrepid1999oil sludge resulting in engine failure
115ChryslerSebring2001oil sludge resulting in engine failure
114ChryslerSebring2002oil sludge resulting in engine failure

See the full list

Oil Sludge News

On the Record

“Chrysler wanted all receipts and documents of oil changes. They stated there was sludge build up. We did come up with quite a few receipts, but not enough. We went round and round with Chrysler, for god sakes it only had 73,000 miles on it, how could it need a new engine?”

2001 Chrysler Sebring Owner, CarComplaints.com

“In retrospect, that took away the margin. More oil means it [the oil] deteriorates slower. If you don’t change the oil on schedule, they [the 2.7-liter V–6s] don’t tolerate a lot of abuse in that regard.”

Clarence Ditlow, Center for Auto Safety

“For everyone having problems with 2.7 motor and sludge build up seizing the motor on your stratus I have some news. Chrysler set up a company strictly to deal with this problem. It is an undisclosed warranty. So ask your Dodge dealer, if they don’t know anything about it they are lying.”

2002 Dodge Stratus Owner, CarComplaints.com