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  #11  
Παλιά 02-02-11, 00:50
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Garage Queens
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Why are there low mileage sports cars that have ruined engines? Why do they have electrical problems?

Ferrari automobiles are perhaps the most problematic. But Why? It seems that most of those who purchase a Ferrari do not often drive them, and when they do they abuse them. Let me explain.

Each morning the lawn is wet with dew. This is because as the temperature drops the dew point is reached and the moisture in the air condenses. This happens in your engine as well. There is air and moisture in the engine. As it sits over night the moisture condenses. It is a repeating cycle. It is actually worse than the outside air. After driving the engine is very hot so as it cools it sucks in a lot of moist outside air.

Remember the products of combustion are water and CO2. The water condenses in the engine during start up and even steam blows by the piston rings for another source of water.

There are additives that help the oil absorb water but if the engine is not started then the water that condensed in all parts of the motor keep it wet. If the car lives near water or worse, salty water, then the situation is compounded. Another thing that makes things worse is mildew and fungal growth, yes it can even grow in oil!

Water is bad but there is another source of corrosion, acids. These result from byproducts of combustion that slip past the piston rings and from fuel dilution of the oil. Again, the oil has additives to neutralize these acids but work only when the oil is splashed around the inside of the engine.

Corrosive products and water in the atmosphere also take their toll on electrical components. Electrical switches are problematic. These are helped by using the switches. When you get in the car and role down the windows and click all the switches they scrape some of the thin corrosion off the contacts. Again, use of the car helps whereas sitting around is detrimental.

Fan and timing belts age at accelerated rates when static and in cold climates. Cold is also bad for plastic, leather and all rubber like parts. Winters are tough on cars. Up north it is cold and the cars get little use. And down south it is moist all the time. Moisture is an independent factor increasing engine wear. Engine tests are usually performed in controlled humidity environments.

People think that taking the car out for a 10 or 15 minute spin will keep it in good shape. Well that is better than nothing because at least everything is splashed down with oil in the engine and some switches are activated that helps remove corrosion. But to burn off excess fuel and water from the oil it must be brought up to full operating temperature. This takes 20 or 30 minutes. Your coolant heats up in as little as 2 – 3 minutes but oil takes up to half an hour to get up to full operating temperature. You should drive the car for another half hour or more after the oil is up to temperature.

People do not realize that “severe” driving conditions that require more frequent oil changes include stop and go city driving of only 20 minute drives or less. This is a severe condition because the oil never gets hot and never burns off the extra fuel or water. For this reason the oil must be changed more often.

Now for my favorite topic, cavitation. This is what accounts for the greatest wear in minimally used engines (in my thinking). Cavitation occurs in fluids when they cannot be moved fast enough. In the bearing the oil is thick at start up (75 F) and yet the parts are moving fast. Vacuum bubbles result. When they collapse there is a huge force that pulls chunks of bearing material from the lining. The chunks may include the full thickness of the bearing. Sometimes pits are seen on bearings and blamed on corrosion or improper lubrication but the culprit is more likely to be cavitation.

People start up their cars and rev up the engines. They impress their friends with the Vroom, Vroom, Vroom over and over again. Then they take the car out for a spin and rev up the RPM. They do this immediately, while the oil is well below operating temperature and relatively thick. I know of engines ruined in this very manor.

The moral of the story is drive your cars often and do not rev them up until the OIL is fully warmed up. Using an oil that is not as thick during the start up period should minimize the effects of cavitaion. This is why I advocate the 0W-XX oils, they are less thick at start up.

aehaas

Τελευταία επεξεργασία από το χρήστη Fairytale : 02-02-11 στις 03:09 Αιτία: μορφή post
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  #12  
Παλιά 02-02-11, 00:51
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Research Paper Reviews
From old posts:
SAE Congress -

I reviewed articles from the SAE conferences on power train and fluid systems in Tampa, Fl of October 2004 and the Paris 2000 conference. See SAE SP-1894 and SP-1550. Here are some excepts:

A New Method of Measuring Aeration and Deaeration of Fluids, Morgan et al:
Air in oil causes oxidation, wasted power, higher oil temperatures, loss of lubricity among other adverse effects. Higher RPM increases aeration, so does increasing oil viscosity. (‘Just FYI).

Effect of Break-In and Operating Conditions on Piston Ring and Cylinder Bore Wear in SI (Spark-Ignition) Engines, Schneider et al:
The rate of wear is much higher within 15-20 minutes of start-up than after reaching normal operating temperature. There was a lot of data but I conclude that the initial start-up time period (first 20 minutes) result is 100 nanometers of wear whereas the steady state wear rate was only 4 nanometers per hour thereafter. (Hence we should be concerned about start-up oil thickness more than running thickness. This justifies the statement that 95 percent of engine wear occurs just after start-up).

Application of a Biodegradable Lubricant in Two Flexible Fuel Vehicles, Jesper Schramm:
Vegetable biodegradable oils were used showing good wear characteristics despite excessive thinning over time. (These may be next! Animal and plant oils have esters as in Red Line oils.)

The SMAC, Under Pressure Oil Aeration Measurement System in Running Engines, Bregent et al:
Oil aging, valve train and bearing problems and thermal problems occur with aeration. Below 110 C there is no problem but as one goes up the aeration ratio increases rapidly. (A cooler running engine from a thinner, faster flowing oil may lubricate better for this reason alone - aeration was a “hot” topic).

Development of the Sequence IV A Valve Train Wear Lubrication Test:Part 1, Sagawa et al:
Viscosity data reveals that the more viscous oil did not significantly alter the cam angle of minimum oil film thickness. Of greater importance is the finding that the higher viscosity oil continued to exhibit boundary layer lubrication. (Ergo thicker is not necessarily better).
The effect of engine intake air humidity was significant so that tests are now done with specified humidity conditions.
It was postulated that fuel dilution of oil would elevate cam wear. Fuel dilution of 4.5 percent did not effect wear. (This would have the effect of lowering the viscosity about 1 grade).

The Effects of Crankcase Oil Viscosity on Engine Friction at Low Temperatures, Cockbill et al:
By using lower viscosity oils there is less friction, improved cold weather starting, improved fuel economy, a savings of starting system components and less wear by increasing the rate of oil pressurization and flow in the upper oil galleries.

Evaluation of Oil Performance Using the Tu High Temperature Engine Test With a View to Extending Oil Drain Intervals, Bouvier et al:
Oxidation and thickening is the limiting factor for oil longevity. Generally modern oils thin only 10 percent then thicken up to 60 percent within as little as 96 hrs. of operation ( -in the accelerated test engine. Let me comment that all test criteria are designed to mimic real engine operating conditions but at an accelerated rate).
There is accelerated acidification and corrosive wear that occurs.
Oil thickening was also time dependent. Thickening at 30,000 km was 2 times more when done over 21 months than over a 10 month period. (Change your oil every spring as I suggested before).

Development of the Sequence III G Engine Oil Certification Test, Clark et al:
Engine tests were made more severe again. (Over the years the oil ratings have improved but this has always been despite the increase in testing severity. It was III ...D, E, F, and is now III G). The oil inlet temperature was decreased from 155 to 150 C. The test was 80 and is now 100 hours. There were 8 oil level adjustments allowed now there are 5. The inlet engine air temperature was raised from 27 to 35 C. The engine load was increased 25 percent.
Despite all this the current 0W-20 oils were still GF-4 compliant and showed minimal wear characteristics as long as ZDP levels were higher than 0.03 percent. (The SM rated oils I have seen so far have levels of 0.08).

Other papers showed how they always consider older engines when formulating new oils for full backwards compatibility.
There was a lot on using thinner oils and how they do not result in excessive wear as previously feared. This is in part because of modern additives.

This stuff was very, very interesting. I will reiterate that you should use the latest, highest rated oil in your car regardless of it’s age. By definition all oils are backward compatible.
Use a grade thinner than you may at first think is best. Always use the oil with the lowest first number in the grade - use 0W-30 instead of 10W-30 and for many reasons use synthetic but mainly because of less wear and tear at start-up!

aehaas

More:
Another question posed to me was the importance of viscosity index. I say look at the numbers not the index. The index does not tell you what thickness the oil is at various temperatures. It is actually outdated and arbitrary. A less arbitrary indication of the change in viscosity with temperature is the viscosity temperature coefficient. From:
Physical and Chemical Properties of Mineral Oils That Affect Lubrication, Douglas Godfrey, William R. Herguth, Herguth Laboratories Inc., 101 Corporate Place - P.O. Box B - Vallejo, Ca. 94590-6968, 1995.


Here is some comparative viscosity data form 3 years ago.
Kinematic Viscosity in cSt of several Mobil 1 oils compared to the Red Line 5W-20:

T(C)* 0W30 * 5W30 * 10W30 * 0W20 * RL 5W20

-20° 1994.8 2225.1 3424.8 1712.7 2995.8
-10° 872.4 944.7 1332.9 730.8 1165.3
0° 428.3 452.9 595.7 352.8 521.4 ( zero F)
10° 231.3 240.1 298.3 188.5 261.8
20° 135.3 138.3 164.1 109.5 144.5 (68 degrees F)
30° 84.6 85.5 97.6 68.3 86.3
40° 56.0 56.0 62.0 45.1 55.0 (104 degrees F)
50° 38.8 38.5 41.6 31.3 37.0
60° 28.1 27.7 29.2 22.6 26.1
70° 21.0 20.6 21.4 17.0 19.2 (158 degrees F)
80° 16.2 15.8 16.1 13.1 14.5
90° 12.8 12.4 12.5 10.4 11.3
100° 10.3 10.0 10.0 8.4 9.1 (212degrees F)
cP @ 150°C
HTHS 3.0 3.1 3.2 2.6 3.3

From: Lubrication, Tribology & Motorsport, R.I. Taylor
Shell Global Solutions (UK), Cheshire Innovation Park, PO Box 1, Chester, CH1 3SH, UK:

We discuss the effect of lubricant viscometry on
piston assembly friction. For the Formula 1 engine, using
the same data as for Figure 4, and assuming a top ring
radius of curvature of 10 cm, Table 6 summarizes the
predicted top ring friction power loss, and the predicted
minimum oil film thickness, for different lubricants:
Table 6:
Lubricant....Power loss (Watts)....Minimum oil film thickness (Pm)
SAE-20W/50........402.................0.76
SAE-15W/40........375.................0.73
SAE-10W/30........313.................0.62
SAE-0W/20..........259.................0.51

People think that a 20 wt. oil is 60 percent thinner than a 50 wt. oil, not so. It is only 30 percent thinner.

aehaas

Previously reported:
I peeked at my neighbors manual from his Mercedes SL 65 AMG V12 biturbo with around 650 BHP?and 700 of torque. It calls for any MB 229.5 certified engine oils that include:
Mobil 1 SuperSyn European Car Formula 0W-40 or Pennzoil European Formula Ultra 5W-30 or Quaker State European Formula Ultra 5W-30 oils.
All 3 of these oils are specified to run at all ambient temperatures from well below freezing from Alaska to Orlando, Florida. Two of the 3 recommended oils are 30 wt. oils. Ferrari is delivered with Shell Helix Ultra 5W-30 but for the Enzo.

Motor Oils - Fuel Economy vs. Wear By Blaine Ballentine, Central Petroleum Company:

Viscosity and Wear
Thinner oils have less drag, and therefore less friction and wear...

Any abrasive particles equal to or larger than the oil film thickness will cause wear. Filters are necessary to keep contaminants small. The other side of the equation is oil film thickness. Thicker oil films can accommodate larger contaminants.

Temperature has a big effect on viscosity and film thickness. As a point of reference, one SAE grade increase in viscosity is necessary to overcome the influence of a 20°F increase in engine temperature. At a given reference point, there is approximately a 20°F. difference between viscosity grades SAE 30, 40 and 50. SAE 20 is somewhat closer to 30 than the other jumps, because SAE 30 must be 30°F higher than SAE 20 to be roughly the equivalent viscosity.

In other words, an SAE 20 at 190°F is about the same kinematic viscosity as an SAE 30 at 220°F, which is about the same viscosity as an SAE 40 at 240°F. This approximation works well in the 190°F to 260°F temperature range.

Ford is bumping up against its CAFE requirements and recommends SAE 5W-20 oil for most of its engines in the United States. It claims SAE 5W-20 is optimal for fuel efficiency and wear.

(If your engine is 20 F cooler running a thinner oil then the viscosity is the same as the next higher weight grade. Also, as wear diminishes with lesser operating temperatures then we have a benefit. Another benefit is that the thinner oil is better at startup where the majority of wear occurs.)

aehaas
Folks, this is it, all I have, enjoy...

Τελευταία επεξεργασία από το χρήστη Fairytale : 02-02-11 στις 03:10 Αιτία: μορφή post
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  #13  
Παλιά 02-02-11, 00:53
Το avatar του χρήστη 120ihatch
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Είναι πολύ ωραία επιστημονική διατριβή πάνω στα λάδια αυτοκινήτων αλλά είναι λίγο μακροσκελής. Προτείνω να την διαβάσετε σε μέρη, κάθε μέρα και από λίγο !


....kalo kouragio :-)

Τελευταία επεξεργασία από το χρήστη 120ihatch : 02-02-11 στις 00:56
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  #15  
Παλιά 23-02-11, 18:16
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race535 has a spectacular aura aboutrace535 has a spectacular aura about
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Αρχική Δημοσίευση από 316e36compact Εμφάνιση μηνυμάτων
Είναι πολύ ωραία επιστημονική διατριβή πάνω στα λάδια αυτοκινήτων αλλά είναι λίγο μακροσκελής. Προτείνω να την διαβάσετε σε μέρη, κάθε μέρα και από λίγο !


....kalo kouragio :-)
316e36compact ευχαριστουμε πολυ για τα κειμενα (τωρα ειδα το thread),αλλα που τα βρηκες;;;;;;

Τα εχω διαβασει εδω και ενα χρονο και εχω γνωρισει μεσω διαδυκτιου και μιλησει προσωπικα στο τηλεφωνο αλλα και μεσω email με τον συγγραφεα.
Ειμαστε μελη και οι δυο σε ενα αμερικανικο Φερραρι Φορουμ και ειναι κατοχος μιας πολυ ομορφης ENZO και μη!
Αναρωτιεμαι ομως που τα ξετρυπωσες!!!
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  #16  
Παλιά 08-03-11, 14:15
Το avatar του χρήστη 120ihatch
120ihatch Ο χρήστης 120ihatch δεν είναι συνδεδεμένος
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Talking

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316e36compact ευχαριστουμε πολυ για τα κειμενα (τωρα ειδα το thread),αλλα που τα βρηκες;;;;;;

Τα εχω διαβασει εδω και ενα χρονο και εχω γνωρισει μεσω διαδυκτιου και μιλησει προσωπικα στο τηλεφωνο αλλα και μεσω email με τον συγγραφεα.
Ειμαστε μελη και οι δυο σε ενα αμερικανικο Φερραρι Φορουμ και ειναι κατοχος μιας πολυ ομορφης ENZO και μη!
Αναρωτιεμαι ομως που τα ξετρυπωσες!!!

αγαπητέ Race, πάνω δεξιά από το post, έχει μια ζυγαριά ....


...σοβαρά τώρα, και εγώ σαν εσένα έψαχνα πληροφορίες για λάδια στο διαδίκτυο, είχα φάει το internet και έπεσα πάνω σε αυτό το άρθρο... και έκανα κάτι μέρες να το διαβάσω...... πρέπει να είναι τρομερός τύπος !!

Τελευταία επεξεργασία από το χρήστη 120ihatch : 08-03-11 στις 14:18
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  #17  
Παλιά 08-03-11, 14:16
Το avatar του χρήστη 120ihatch
120ihatch Ο χρήστης 120ihatch δεν είναι συνδεδεμένος
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Αρχική Δημοσίευση από Fairytale Εμφάνιση μηνυμάτων
Τς τς τα σέβη μου...
C U out there
ευχαριστώ πολύ !

(δεν έκανα τίποτα, το μόνο που έκανα ήταν να το ανεβάσω εδώ)

Τελευταία επεξεργασία από το χρήστη 120ihatch : 08-03-11 στις 14:30
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