Engine sludge time bomb

First of all I am impressed with the depth of technical expertise I have seen in this group and appreciate the advice youall have given me
in the past. Because of this you have me very concerned about "engine sludge" in my 99 4 cyl Camry. I get any uneasy feeling that I am setting on a time bomb that is going to suddenly destroy my engine. I bought the car new and have had no problems with it except what I mentioned a couple of weeks ago of noticing the car using a quart of oil (again) after a 1200 trip but not using any between oil changes when we went only on short trips and city driving. The car has 68000 miles on it now and I have personally changed the oil /filter every 4-5000 miles since I bought it except once when I told the dealer of using oil on a long trip 3 yrs ago. They changed the oil replaced the filter and I took it back to them 1500 miles later and it never used a drop since I hadn't taken any long trips. I take good care of this car and my 93 Camry (which I bought new also) and don't "abuse" them. I have not kept my oil receipts but do have a log of the dates/mileages of when I did change the oil/filter. So - what should I do or what should I expect? I would appreciate your comments Thanks
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You can allay your fears in literally 2 minutes. Pop the bonnet, unscrew the oil-filler cap from the cam-cover,..look inside. On my 2.2L 2nd-handy there was a thin layer of black gunk present there on the step in the casting immediately underneath the oil-cap. If yours is essentially clean with perhaps an opaque-honey coloured varnish, you have no worries. If there is a layer of black goop,..then I'd start changing the oil/filter twice as often. We are after-all talking about $20 for oil/filter and 20 mins work at home. Its no biggy, as they say.
The point is, sludge forms *all* over the engine internals. If there's none in the oil-filler hole, there will be none anywhere else.
Further with mine:
If there are oil-leaks on the floor under your car,..and they are not coming from the distributor area or the cam-cover gasket,..have a look at the crankshaft pulley area. Is there oil wetness around there? If so, you need to have the oil-seals replaced on the front of the engine. If there is wetness around the transmission bell-housing drain hole (underneath),..the rear crank-seal may also be nutted. That can wait if its only a small amount.
Jason
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snipped-for-privacy@att.net wrote:

I have the same car as you, and was also concerned about the sludge problem. I was changing my Mobil 1 5W30 full synthetic every 5000 km until I pursued the following avenue:
One scientific measure of whether you have a sludge problem is to get a used oil analysis by a lab that has a plasma spectrometer. Blackstone Labs (http://blackstone-labs.com ) is one such lab with reasonable prices and excellent service. I find that springing for their Terry Dyson package (i.e. a plain-language interpretation of the results) once a year is worth it. He can see if there are precursors to sludge in your used oil, which will help guide you in deciding how frequently to change your oil.
bobistheoilguy.com contains a lot of useful information if you're prepared to read a bit.
Me, I change my oil every 10,000 km now, after having proven that this is a safe interval for the particular mix of city/highway that I do in the climate that I live in. (Roughly 80% city by km driven in Ontario, Canada.)
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snipped-for-privacy@att.net wrote:

I agree with Jason and N.I. and would only add that if the majority of your driving is short trips then at least once a month (preferably more often) you take a short trip of sustained highway speeds for at least 20 min. out and 20 min. back. This will bring all lubes up to a heat point that will let them evaporate all the moisture out and cause all moisture in the air cavities to evaporate out. This moisture is what causes sludge when it is allowed to accumulate and mix with oil vapors then gel. davidj92
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Dude, relax. As I've often pointed out, I've dealt first hand with this sludge garbage for about six years, and have not seen ONE example of a sludged engine with a reasonable service history. By reasonable I mean oil changes at consistent 7500 miles or less. So, just change your oil, and you'll be alright. Besides, the 5S-FE like yours isn't the one with the problem, it's the V6.
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City driving in cold weather of 5 miles or so is bad for a motors oil as it never heats up enough to cook out moisture and polutants. When you drove on the highway if it was old oil it could have been extremely diluted with gas and moisture which cooked out lowering the level. Ive seen this many times.
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With regular 5,000 miles oil change intervals you should be just fine. When I check the dipstick (weekly - Saturday morning, first thing - cold engine) I look for oil level and condition. You can observe the oil gradually darkening over time. It is supposed to do that because there are detergent additives to hold contaminants in suspension. The only way sludge can develop is when the oil is overwhelmed by contaminants that no longer stay in suspension and drain out with the used oil. So if you check and change the oil regularly, there is no problem. If you chose to switch to synthetic oil, like Mobil 1, then you are super protected. ========copied from someone else: *Just what is synthetic oil*? Technically speaking, synthetic lubricants are made by chemically combining, in a laboratory, lower-molecular-weight materials to produce a finished product with planned and predictable properties. Don't be confused by this technical double-talk. What this means is that synthetics are custom-designed products in which each phase of their molecular construction is programmed to produce what may be called "the ideal lubricant." This process departs significantly from that of petroleum lubricants, whose physical components, both desirable and undesirable, are inherited from the crude oil from which they are refined. Crude oil possesses thousands of varieties of contaminants, depending upon the oil's geographical and geological origins, which no amount of refining can entirely remove. Corrosive acids, paraffins and other waxes, heavy metals, asphalt, naphthenes and benzenes, as well as countless compounds of sulfur, chlorine, and nitrogen, remain in the finished product. Equally as important, petroleum oil molecules, as contrasted to uniform-sized synthetic oil molecules, vary significantly in size, shape, and length. When your engine heats up, the smaller molecules evaporate, while the larger ones tend to oxidize and become engine deposits. As a result, refined petroleum lubricating products differ widely in their overall quality and performance. The presence of and the resulting drawbacks of the undesirable constituent elements lie at the very root of the considerable performance differences between synthetic and petroleum-based motor oils. Contrary to what many may believe, synthetic lubricants are not a recent development. As early as the 1930s, Standard Oil of Indiana conducted research into synthetic oil. More serious development and production was commenced by the Germans during WWII, as their conventional lubricants congealed and froze on the Eastern front and stalled their advances into the Soviet Union. As jet engines were developed after the war, it soon became evident that conventional lubricating oils couldn't withstand the high temperatures and pressures, and synthetics came to be used in all military commercial jet aircraft engines. Then in the 1960s history repeated itself, and it was again cold weather that spurred further development work as the U.S. Army needed better lubricants for Arctic and Antarctic use. Still later, NASA specified synthetic-based lubes for all space vehicles, including the Space Shuttle. Today's automotive synthetic lubricants have evolved as an almost direct result of these demanding military and extraterrestrial lubrication requirements. The U.S. Department of Energy lists no fewer than *sixteen* performance parameters for any modern automotive motor oil. These are:
-Low temperature fluidity (low pour point)
-Low volatility...i.e. resistance to evaporation and resultant oil thickening...good oil economy, additional engine protection
-High temperature oxidation resistance (of the oil itself)
-Lubricity...the oil's slipperiness
-Thermal stability...resistance to performance loss due to temperature change
-Compatibility with engine metals, elastomers (i.e. "rubber" seals), oil filter elements, paints, and finishes
-Wear protection and film strength
-Freedom from deposit formation...good dispersant and detergent characteristics
-Compatibility with other engine oils and additive packages
-Extended drain capability
-Water stability...propensity to remain separate of water molecules
-Corollary effects on an engine's octane requirements
-Ambient-startup protection...ability to protect against oil starvation during initial startup
-Anti-rust properties
-Compatibility with catalytic emission control systems
-Compatibility with alcohol-containing fuels
Chief among the areas in which the pre-planned and predictable properties inherent in premium synthetic lubricants significantly surpass those of premium petroleum oils are: low temperature fluidity... and thus improved ambient startup protection; low volatility (higher boiling point...greater resistance to evaporation); high-temperature thermal stability; oxidation resistance; lubricity; fuel economy; film strength, and wear protection; extended drain capabilities; water stability; and high *natural* detergent characteristics (resulting in a cleaner engine with less additive content). synthetic oils are also renowned for their high-temperature thermal stability. Superior high-temp stability ensures and engine lubricant's capacity to protect vital engine components during very-high-temperature operation, such as hot summer driving, sustained high-speed driving, repetitious stop and go metropolitan driving, driving in mountainous terrain, pulling a trailer, or any driving with a small harder-working piston or rotary engine. Underhood temperatures also take a quantum leap with the use of power options, especially air conditioning, and because of emissions devices and emissions-related engine redesign. It is important to note that, even though the dash gauge may register only a 200F or so water/coolant temperature, the temperature of the sump and of all the assorted bearing surfaces significantly exceed the water temperature, and often surpass 500F on the piston ring and cylinder wall areas. These high-temperature surfaces serve to rapidly decompose petroleum oil and additives, as well as contribute to their shorter service life, while the synthetic is largely unaffected. Beyond the protection afforded an engine during these particular instances of high-operating temperatures, high-temp thermal stability moreover permits an engine oil to deliver overall extended service life (significantly longer drain intervals) in all driving conditions, because it prevents the phenomenon of sludge and carbon deposit formations on critical engine parts (valves, valve guides, oil channels, lifter assemblies, piston rings, et al.) due to oil thickening, a problem commonly attributable to petroleum oil breakdown at high temperature. As these deposits accumulate in the oil circulatory system, oil flow drops, thus accelerating engine wear. To the user of synthetics, the benefits are (1) reduced wear of critical engine components; (2) significantly reduced sludge and varnish... a cleaner engine; (3) reduced engine drag due to uniform viscosity; and (4) increased fuel economy due to reduced component wear. "Film strength" refers to the amount of pressure required to force out a film of oil from between two pieces of flat metal. The higher the film strength, the more protection is provided to such parts as piston rings, timing chain, cams, lifters, and rocker arms...wherever the lubricant is not under oil-system pressure. Synthetics routinely exhibit a nominal film strength of well over 3,000 psi, while petroleum oils average somewhat less than 500 psi. The result is more lubricant protection between moving parts with synthetics. The remarkable ability of synthetic oils to reduce internal operating temperatures is far too important to ignore, since high operating temperatures contribute directly to premature failure of mechanical components and gaskets and seals. Coolant (i.e. water/antifreeze) cools only the upper regions of an engine. The task of cooling the crankshaft, main and connecting rod bearings, the timing gear and chain, the camshaft and its bearings, and numerous other components must borne entirely by the oil. Popular Science article on synthetic oils, veteran race car driver Smokey Yunick was quoted: "When you disassemble an engine that's been run on petroleum oil, if you examine the rings and cylinder bores with a glass you'll see ridges and scratches--that's the wear going on. With polyol (a variety of synthetic), when you take the engine apart everything has the appearance of being chrome-plated. In the engine we ran at Indianapolis this year we used a polyol synthetic. When we tore the engine down, you could still see the original honing marks on the bearings...no wear at all. We put the same bearings back in because the crankshaft never touched the bearings. I've never seen that before."
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<snip>
<snip>
Daniel,
There appears to be a contradiction. You say sludge is caused by the oil being overwhelmed by contaminants, while the article you copied says it is due to high temperature breakdown of the oil. Maybe it's both?
Paul
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That sludge problem isn't what you should be worried about. You're much more likely to have problems with your O2 and/or fuel sensors or better yet the IAC valve...probably the most widespread problem among all Camrys of your generation. Those problems should keep you awake at night, the sludge thing is pretty obscure.

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