2011 BMW Other Sludge inside engine

Tiny
NSGARO
  • MEMBER
  • 2011 BMW
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 20,000 MILES
I notice some sludge inside my engine. What is the best way to clean the engine and keep it clean
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Friday, September 19th, 2014 AT 1:20 AM

2 Replies

Tiny
CARADIODOC
  • EXPERT
Regular oil changes with a good-quality oil. It's the additives that help suspend the junk and move it to the filter. If the problem persists, you might try a different brand of oil. Experts will tell you there's two different kinds and it depends on where it comes from out of the ground. Pennzoil is one that has a wax in it that isn't found in most other oils, and I've had very bad luck with it many years ago. Other people love it.

Probably more important is to stick with one brand. There are additives for detergents, seal conditioners, corrosion inhibitors, friction modifiers, and viscosity index improvers. Many of those additives are not compatible with the additives found in a different brand of oil. During an oil change when up to five quarts of old oil is drained out, there can be as much as two quarts stuck in the passages that doesn't drain out. Typically those additives wear out in about 3,000 miles, but they're still in there. One rubber seal conditioner may be rendered ineffective by the additive in a different brand of oil.

The problems I've seen most often involve new leaks, and it always appears to be not the brand of oil but that the person SWITCHED brands of oil. In a few cases where leaks developed, they mostly cleared up when the person went back to the oil they were using. There's no reason to think detergents wouldn't act the same way.

Excessive blowby causes a lot of sludge too. You don't have nearly enough miles yet to think about that, but also consider how much short-trip driving you do. I have almost 420,000 on my daily driver engine and there's no sludge at all in it. I won't tell you when the last time was that I changed the oil, but I count it in decades now, not years! (I'm not recommending you abuse your engine this way. It just goes to show what some engines are capable of). I live in a rural area and every trip is between 10 and 40 miles. If you drive a lot of short distances, get out on the highway once a week for 20 or 30 miles to get the engine really warmed up. That will melt the sludge buildup so it can get carried to the filter.

I'm not a believer in other additives for your oil unless you're trying to solve a specific problem while avoiding the proper repair. Even the cheapest oil has all the additives to get the job done. Every few years the car manufacturers specify an improved oil, and the oil companies do a good job of meeting those requirements. You really can't find outdated oil unless someone stockpiled a bunch years ago. Your owner's manual will specify an "S" rating if you have a gas engine, ("S" is for "spark ignition"). Years ago the best was "SF". The next improvement of significance got a rating of "SG". If your car called for "SF" when it was new, you can use anything that came after that, like "SG", "SH", etc, but you're not supposed to use "SE". If "SJ" is the current standard today, you won't even find any older designations on the store shelves.

If you have a diesel engine, the same container of oil will have a "C" rating for "compression ignition". I don't even know what the current rating is because only the latest one will be available in stores. This is where most of the improvements were made. Oil for diesel engines has to stand up to high-speed turbochargers without getting thrown off the bearings, much higher temperatures without breaking down, and it has a real lot more soot to keep in suspension so it gets carried to the filter.

One problem that occurs on some gas engines is high heat caused by the oil filter sandwiched right next to a hot exhaust manifold or turbocharger. Toyota had a big problem about 15 years ago with "oil coking" from the filter sitting right next to the exhaust manifold. We don't hear about that anymore but you might want to look at your engine. If it looks like heat could be a problem, consider changing the oil more frequently.
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Friday, September 19th, 2014 AT 2:21 AM
Tiny
WRENCHTECH
  • EXPERT
I totally agree with Caradiodoc's points here.

All I would like to add is DO NOT attempt one of these engine flushes that a lot of the quick stops try to sell. If you start to dissolve that stuff that quickly, it will start breaking off in chunks and circulating through the engine which will restrict very important lubrication passages and could lead to engine failure. More frequent oil changes is the only safe method.

There is no good cure for this problem once it occurs. The key is to not let it happen in the first place.
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Friday, September 19th, 2014 AT 4:58 AM

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