Thin oil/Piston ring seal

[buster]

http://www.carcraft.com/techarticles/oil_tech

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Another reason to perhaps shorten drain intervals for performance engines is that oil is an important component of ring seal. If engine oil is contaminated with water, the water evaporates almost immediately around the rings, reducing ring seal and horsepower. Several years ago, we witnessed this firsthand at the U.S. Nationals when John Lingenfelter's small-block-Chevy-powered Pro Stock truck suffered an internal water leak. Once the water mixed with the engine oil, the 9,000-rpm engine lost double-digit power, which cost him the race.

The ultimate seal with piston rings is assisted with engine oil. The highest friction loss in an engine is found between the rings and the cylinder wall. Quaker State's research indicates that a too-thin oil can actually vaporize at the top ring, sacrificing ring seal.

Fuel is another contaminant that is often found in engine oil. Fuel can enter the oil from several places, most commonly as blowby past the rings. Even though we think of fuel as easily evaporated, according to Farner only the light ends of fuel evaporate at room temperatures. The heavier ends require temperatures as high as 450 degrees F to fully evaporate, which means that even at 300-degree oil temperatures, there can still be residual fuel that tends to reduce your oil's effective performance.

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For street engines that do not suffer this kind of track-day abuse, merely pouring in a synthetic does not mean that you can radically extend service drain intervals. Petroleum-based oils do not lose their base lubrication characteristics, what does suffer with use are the additive packages added to the oil. Synthetics are no different. For example, Farner says that for every pound of fuel burned in an engine, the combustion process also creates a pound of water. Some of this water will eventually end up in the oil pan. If the engine rarely sees sump temperatures that exceed 212 degrees F (water's boiling point), the water quickly mixes with another combustion byproduct--sulfur--to create acids that can eventually eat bearings if the oil is not drained.

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[jorton]

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Some of this water will eventually end up in the oil pan. If the engine rarely sees sump temperatures that exceed 212 degrees F (water's boiling point), the water quickly mixes with another combustion byproduct--sulfur--to create acids that can eventually eat bearings if the oil is not drained.

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ohoh. Best way to replenish additives? 3 month OCI.

 

[G-MAN]

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Several years ago, we witnessed this firsthand at the U.S. Nationals when John Lingenfelter's small-block-Chevy-powered Pro Stock truck suffered an internal water leak. Once the water mixed with the engine oil, the 9,000-rpm engine lost double-digit power, which cost him the race.

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No chance the loss in HP was the fault of the thick viscous goo that resulted from the ingestion of water that turned the 30 wt racing oil into 90 wt honey?

 

[buster]

You can design a motor oil (Amsoil/M1) to fight off many of the contaminants he referred too. I don't completely buy into it.

 

[Steve S]

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Some of this water will eventually end up in the oil pan. If the engine rarely sees sump temperatures that exceed 212 degrees F (water's boiling point), the water quickly mixes with another combustion byproduct--sulfur--to create acids that can eventually eat bearings if the oil is not drained.

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ohoh. Best way to replenish additives? 3 month OCI.

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For engines that do not reach a high enough oil temps to evaporate the moisture. But remember the oil reaches higher temps than sump temps when being pumped smooshed theough the bearings squeezed from between the cam and lifters,rockers and from under the pistons.

 

[Lonnie]

One thing that clouds the issue is that most Xw-20 oils are just better quality oils than the Xw-30,40,50 oils.

 

[Steve S]

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Several years ago, we witnessed this firsthand at the U.S. Nationals when John Lingenfelter's small-block-Chevy-powered Pro Stock truck suffered an internal water leak. Once the water mixed with the engine oil, the 9,000-rpm engine lost double-digit power, which cost him the race.

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No chance the loss in HP was the fault of the thick viscous goo that resulted from the ingestion of water that turned the 30 wt racing oil into 90 wt honey?

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No because the water / coolant "steam cleans" the oil and additives from the rings and pistons and cyl walls ,as mentioned oil is important in the ring seal . So basically no oil = no lube =massive friction and loss of ring seal = severe loss of power and finally engine damage.

 

[Steve S]

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You can design a motor oil (Amsoil/M1) to fight off many of the contaminants he referred too. I don't completely buy into it.

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Depends on the operation of the vehicle .look at the uoas and how the oils hold up some times "for example" Amsoil will show stellar results and sometimes not.

 

[Steve S]

looking at the hp# not really a whole lot of difference. What about engine durability?

 

[LargeCarManX2]

I tend to feel that thicker oil would be better in the ring area. If a film of oil is pushed up and past each ring via the ring spacing and the upper oil ring keeping it from entering the combustion chamber....I would think a fully synthetic of 50w to 60w would be the best choice for racing.

The 50w or 60w film thickness and sure shear strength would keep the rings/cylinders better lubed!

 

[oilyriser]

Thick oil might not reach the top ring as well as thin.

 

[buster]

Steve good posts. You're right.

Lonnie that is true.

Somewhere on here there was a link to a study done that showed the oil file was thicker at the top of the ring with 20wt oils vs 30wt and 40wt oils.

 

[yannis]

Dr.AeHaas was the first to post this image to BITOG.

http://theoildrop.server101.com/forums/s...true#Post898236

 

[Lonnie]

Buster, it's been my experience that overall Xw-20's are very good oils, often better than their thicker cousins. I think they carry a better additive package and maybe the base stocks are better too. This has proven to be true in large fleet operations using oil's from the same manufacturer.

 

[moribundman]

My '96 Audi has low tension rings. There is a distinct increase in oil consumption if go from a 5W-50 or 5W-40 oil to 5W-30. I'm talking about a difference of 1/8 to 1/2 quart more oil consumption per 1k miles. This effect is most noticeable when doing a fair amount running the engine under high-vacuum conditions (engine braking, as in city driving -- think steep hills) or when driving hard (prolonged high RPM driving and lots of down-shifting)Driving long distance at street-legal US highway speeds doesn't show any remarkable difference in oil consumption between oils.

Also, Group III oils result in my engine in lower oil consumption than do Group IV and Group V oils.

I see lowest oil consumption with Castrol 5W-50 and Chevron Delo 400 15W-40. Consumption was highest with M1 0W-40 and Red Line 5W-30.

Consumption is between extremes with:

M1 5W-40
Pennzoil Platinum 5W-40
Valvoline 5W-40

I stopped giving Mobil my business due to their unwillingness to clearly say if M1 is Group IV. I stopped using Pennzoil, because it's hard to find and because it costs $7 a quart. I'm using Valvoline because it works just as well as the other oils and because it costs less and because it's available at every NAPA.

 

[Shannow]

Mori,
for decades, the only oils available down here were 20W-50...it went in everything, and every manufacturer specified it.

Shell introduced a 15W-30 in the early 80s.

Nearly everyone who tried it had horrific oil consumption

(down here, 1 qt/5000km was deemed bad enough for a rebuild, as nothing consumed much with 20W-50)

Now the manufacturers are specifying xw-30s, they are increasing sump capacities and lengthening dipsticks, to re-define "normal"

 

[mechtech2]

I was around in the 60s-70s-80s, and 1 qt in 3000 [5000km] miles was very good consumption.
A rebuild because of this consumption back then? Not a chance!
Sumps are getting smaller, not bigger, and lengthening the dipstick would serve no purpose.

 

[Shannow]

mechtech, I'm not talking about the U.S. which was using 30 weights, but Oz, where everything was 20W-50.

1 litre per 5,000km was considered abnormal, and worthy of rings and guide seals.

As to bigger sumps, and longer dipsticks, they have been used, and recently.

GM had problems with their V-6s with low tension rings and 30 weight oils, as Australians were emptying the sumps between services (10,000km). Holden first replaced the dipstick, so that the sump was overfilled by a litre, and thus widened the range from full to add. They later increased the sump size further.

Oz drivers never anticipated using a sump worth of oil between services in a new car.

That level of consumption was entirely beyond our comprehension, based on history.

 

[buster]

Low tension rings has a lot to do with it IMO. I also think people should be breaking in their cars with more WOT, although many say most engines are already broken in by the time you drive it off the lot.

 

[moribundman]

I don't know if Honda runs every engine of a dyno before installing it. My Audi engine required no traditional break-in. However, the engine losened up very noticeably over the first 60k miles (took me only a bit over one year). O-60 times dropped. The engine runs now, at almost 160k miles, better than ever. It does however need more oil than it used to need. Then again, I drive mostly WOT or FT or I coast, all of which contributes to oil consumption.