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No sludge here!


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Have noticed a number of references to oil sludge issues on this forum, esp with regard to a certain Asian family of automobiles. Turns out its a bit more widespread ... "Chrysler, Dodge, Toyota, Lexus, Volkswagen, Audi and Saab have had sludge problems". Its made the NY Times sunday edition, thought a few of you would be interested ...

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http://www.nytimes.com/2007/02/04/automobi...amp;oref=slogin

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Sludge problems are not new by any means. At one time engines were thought to last under 100,000 miles and this was expected and accepted. The fallacy of this from the earliest days is exemplified by the Chrysler Marine line of flathead sixes, which were mechanically very similar to engines used in cars. The marine engines lasted far longer, usually failing only from neglect, abuse or coolant issues no matter how many hours were on them. From the 1950's, car-wise people honored 1,000 mile to 2,000 mile oil change intervals as a magic bullet to keep their engines going as long as they liked.

The NYT article cites an engine design engineer for one of the troubled motors as saying that reduced oil capacity to make oil changes less expensive reduced the motor's tolerance to oil change intervals. This makes it clear that the factors that determine whether or not an engine design is pushing the envelope is known and under the control of the engine design team. Also, a quick improvement can be had by changing to an oversize oil pan that holds another quart of oil.

All Northstar designs show a great deal of sensitivity to the sludge issue by their 7.5 quart oil capacity and the oil life indicator, which estimates sludge factors and ZDP remaining from time, temperature, and engine usage as available in great detail from the PCM. Remember that the next time you pay for eight quarts of oil at an oil and filter change.

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-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
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Yes, I was Jims_97_ETC before I changed cars.

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All Northstar designs show a great deal of sensitivity to the sludge issue by their 7.5 quart oil capacity and the oil life indicator, which estimates sludge factors and ZDP remaining from time, temperature, and engine usage as available in great detail from the PCM. Remember that the next time you pay for eight quarts of oil at an oil and filter change.

The reason for the 7.5 quart oil capacity in the Northstar is to provide cooling capacity if the engine enters the limp home mode due to a total loss of coolant. The extra oil pan capacity is also there to provide adequate lubercation during spitited driving where excessive g's are incountered. The engine was validated with 5 quarts of oil in the sump and the engine tilted 45 degrees on the dyno....

Kevin
'93 Fleetwood Brougham
'05 Deville
'04 Deville
2013 Silverado Z71

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I heard it slightly different, but basically what KHE is saying...

Anyone who had a Z-28 or Trans Am in the mid to late 80's is very familiar with the overheating issues....

I was told that the 8 quart oil capacity was to address that.... a 60% increase in your pool of oil does a great job of cooling the motor...

Thus, LS1 C5 Corvettes and Northstars have the 8 quart oil capacity.... which to me, is very cheap insurance against all sorts of issues....

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Kevin is correct. I once asked the Guru why the Northstar had a 7.5 qt. capacity when I was new to the northstar and this site. He said the because the Northstar was designed as a high performance engine, the oil capacity was to guaranty that the engine would not starve for oil in with a 1G lateral force at WOT.

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I think that what the Guru said at the time is probably defnitive as a driver. I also go with Patrick7997 that "extra oil capacity is cheap insurance for all sorts of issues." We have 40% more ZDP in a crankcase of 7 quarts than a crankcase of 5 quarts, the oil circulates slower so it transfers more heat out the oil pan and the engine runs cooler, etc.

We aren't totally exempt from the sludge issue. The sticking rings seen in some 1993-1999 engines may be put in this category.

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-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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We have 40% more ZDP in a crankcase of 7 quarts than a crankcase of 5 quarts, the oil circulates slower so it transfers more heat out the oil pan and the engine runs cooler, etc.

10-4 to that.

Regardless of the original design intent of the large sump, it's good to recognize the benefits of that extra capacity, in terms of extended drain intervals, good engine protection due to the added capacity of the large sump.

Think of it in terms of extremes. If you only had a one quart sump, that oil would be flat used up in no time. If you had a 50 quart sump, that oil might last 5 years or more. More oil is better. I'm glad we have the great protection of a large oil sump.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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Sludge and sticking rings are two completely different issues, caused by completely different circumstances. Having said that, they are not mutually exclusive, so a car with sludge might have stuck rings, and vice-versa.

In the Northstar, the engine design places the top piston ring VERY close to the flame front, subjecting it to higher than normal temperatures. The cylinder walls have the much talked about agressive honing pattern that contributes to long engine life....and higher than expected oil consumption. The motor oils being produced from 1993 - 1999 contained VII's which were not quite able to withstand the kind of temperatures that the N* subjected them to. Add to that those shade tree mechanics that used heavier oil to slow consumption, wider viscosity ranges, overfilling the engine with oil, and driving the car very gently, all contributed to increasing the amount of those VII's burning in the ring area.

Sludge is caused by short trip driving, particularly in cold weather when the water vapor normally produced by combustion, is not driven off completely. Poor crancase ventilation exagerates this problem, as well as the "percieved" sludge issues that only appear where the driver can see...in the cooler, dead area of a filler neck that some car makers are so fond of.

The Northstar engine is not sludge prone in my experience, mine being like new inside (where I can see of course) with 85,000 miles on it, changing by the OLM.

Another reason the Northstar oil capacity is larger, one that most of us have NOT heard, is to make sure that the "add oil" message would not come on before the next OLM recomended oil change was called for. The engineers fully expected usage of 1qt./2 or 3,000 miles, so they gave you at least 3 quarts to play with until you had to open the hood. To do anything less would have IMMEDIATELY earmarked these engines as junk in 1993.

Never underestimate the amount of a persons greed.

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how do you know if you have sludge and how do you get rid of it if you do? Any thing you can buy and that'll thin it out without destroying your seals? I just bought this brand new used Deville and they're making sludge sound like the killer of all used engines.

Everyday Is Saturday!

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Remove your oil fill cap. Shine a flashlight down in the cam cover and if you have a small inspection mirror, stick that down there for a better look. I doubt you'll see any sludge.

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Remove you oil fill cap. Shine a flashlight down in the cam cover and if you have a small inspection mirror, stick that down there for a better look. I doubt you'll see any sludge.

I see nothing but cleanliness! :lol:

Regards,

Warren

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http://i70.photobucket.com/albums/i101/Jim...mbearingcap.jpg

Sludge? What sludge? The sludge that oil companies and oil additive producers love to show on cable TV networks?

There are many variables to consider. No doubt there are engines that suffer very short trips twice a day for their entire lives that have the potential for sludge buildup. Then there are folks who are 'too busy' to have any routine service done on their rides. Toyota and the others mentioned in the NYT article increased the potential for sludge formation when the engine was still a blueprint.

The picture is my Northstar at 150,000 miles; credit to the OLM, modern oil chemistry, and avoiding short trips.

Jim

Drive your car.

Use your cell phone.

CHOOSE ONE !

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I could eat a meal off the valvetrain. 156k miles, oil changes according to OLM with either Pennzoil, Havoline, or Valvoline oil.

Jason(2001 STS, White Diamond)

"When you turn your car on...does it return the favor?"

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When my original motor was pulled out at 116,600 miles it looked as clean as the day it first drove off the lot under the cam covers.

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-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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Sludge and sticking rings are two completely different issues, caused by completely different circumstances. Having said that, they are not mutually exclusive, so a car with sludge might have stuck rings, and vice-versa.

In the Northstar, the engine design places the top piston ring VERY close to the flame front, subjecting it to higher than normal temperatures. The cylinder walls have the much talked about agressive honing pattern that contributes to long engine life....and higher than expected oil consumption. The motor oils being produced from 1993 - 1999 contained VII's which were not quite able to withstand the kind of temperatures that the N* subjected them to. Add to that those shade tree mechanics that used heavier oil to slow consumption, wider viscosity ranges, overfilling the engine with oil, and driving the car very gently, all contributed to increasing the amount of those VII's burning in the ring area.

Sludge is caused by short trip driving, particularly in cold weather when the water vapor normally produced by combustion, is not driven off completely. Poor crancase ventilation exagerates this problem, as well as the "percieved" sludge issues that only appear where the driver can see...in the cooler, dead area of a filler neck that some car makers are so fond of.

The Northstar engine is not sludge prone in my experience, mine being like new inside (where I can see of course) with 85,000 miles on it, changing by the OLM.

Another reason the Northstar oil capacity is larger, one that most of us have NOT heard, is to make sure that the "add oil" message would not come on before the next OLM recomended oil change was called for. The engineers fully expected usage of 1qt./2 or 3,000 miles, so they gave you at least 3 quarts to play with until you had to open the hood. To do anything less would have IMMEDIATELY earmarked these engines as junk in 1993.

Thank you Johnny, for stepping up and making this point, I was going to reach out to the knowledgable one to have him comment on the sticking rings. I knew it was NOT related to sludge, I just didnt know why.... Thanks

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how do you know if you have sludge and how do you get rid of it if you do? Any thing you can buy and that'll thin it out without destroying your seals? I just bought this brand new used Deville and they're making sludge sound like the killer of all used engines.

The replies to your post by other members are correct, if you can see it with a flashlight when looking into the filler hole.......you might have a sludge problem. It looks a little like mayonaise at first, then gets thicker and darker over time, eventually looking like old brown axle-grease.

In reality though, it is extremely rare that sludge itself will ever cause an engine to fail, or even be harmed. Sludge would need to get so bad, so thick, that it would restrict the flow of engine oil to the moving parts of the engine. That scenario is very UN-likely to happen with modern engines and lubricants. "They're" making sludge sound like the killer of all engines for a reason....to seperate you from your hard-earned money!

If you do find a problem, the trick is to determine exactly what is causing the problem so that an effective course of treatment can be formulated. (Boy, I must be learning a lot from those TV drug ads! :) )

There is no "fix in a bottle" for sludge, or a sludge prone engine. Nothing that you can add to the engine oil will eliminate the sludge and keep it away. If your driving cycle is such that the engine never gets completely warm for 20 minutes or more......you're 'gonna get sludge. If you have a mechanical problem that increases the amount of water in the lubrication system...you're gonna get sludge too.

I've noticed too that cold weather increases the amount of condensation present in an engine, don't be too alarmed if this happens, or if you can see water droplets under the oil cap when it is very cold out. That's a harmless event that will likely go away when warm weather returns. In the meantime, motor oil additives will keep the moisture from harming anything.

Never underestimate the amount of a persons greed.

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I've noticed too that cold weather increases the amount of condensation present in an engine, don't be too alarmed if this happens, or if you can see water droplets under the oil cap when it is very cold out. That's a harmless event that will likely go away when warm weather returns.

Let me take a wild guess here Johnny. Could you be talking about the GM 3800? My wifes is terrible for that. The underside of the cap is all wet and has the milky oil goop stuff on it. I was worried about a head or intake gasket. It only happens in the winter though and has been going on for years. Doesn't use coolant and the PCV is functional. Don't matter how long you drive it either. Very strange animal. BTW, it's got 136K on it and still going strong ('96 Bonneville).

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A sheet metal valve cover, as opposed to cast cam or valve covers, will be less likely to get engine heat to evaporate away the water condensation in the top end. Just keep the oil changed, make a point of driving it long enough to get the engine thoroughly warmed up at least once a week, make sure that the PCV is working OK, and let your long experience with the 3800 reassure you. There are lots of sheet metal valve cover OHV engines out there that get some sludge in the valve covers in the wintertime. The problems come when it gets so bad it clogs the oil return lines and the oil accumulates under the valve covers. That gets the oil level lower in the oil pan and encourages oil leakage at the valve covers and even oil burning through the valve guides. Then, there are some cars that accumulate sludge in the lifter valley, or even parts of the crankcase...

CTS-V_LateralGs_6-2018_tiny.jpg
-- Click Here for CaddyInfo page on "How To" Read Your OBD Codes
-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data
-- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC
Yes, I was Jims_97_ETC before I changed cars.

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There are lots of sheet metal valve cover OHV engines out there that get some sludge in the valve covers in the wintertime.

The ONLY place it gets any sludge is under the cap.

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The ONLY place it gets any sludge is under the cap.

I've had several different engines that have had this little problem, not just the 3800. Your post confirms that this situation is harmless, 136,000 miles! Can't get much better than that! Good job! Make sure that the thermostat is keeping the engine in the operating range, but I don't really see a problem. This is just one of those areas that are prone to visible condensation.

Never underestimate the amount of a persons greed.

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