Good info on engine oil

Discussion in 'Archived Threads 2001-2004' started by Henry Carmona, Jul 13, 2002.

  1. Henry Carmona

    Henry Carmona Screenwriter

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    What oil do you guys use? Its 10W-40 for my truck in the TX heat and 5W-30 in winter.
    Thought some of you gear heads would like some info. If not to educate you, at least to pass the time [​IMG]
    Viscosity is the measure of the internal friction in a liquid or the resistance to a flow. Because Viscosity changes with temperature and sometimes also with pressure, it is also important that when different fluids are compared that the measurements were conducted under the same temperature and pressure conditions.
    The multi's have viscosity index improvers. Those are chemical additives that are added to finished lubricants to improve the viscosity index.
    A lubricant additive, usually a high-molecular-weight polymer, that reduces the tendency of an oil to change viscosity with temperature. Multi-grade oils, which provide effective lubrication over a broad temperature range, usually contain V.I. improvers.
    While Viscosity Index Improvers can enhance viscosity index (VI), they can break down under shear or over time, resulting in diminished performance.
    The viscosity index is an arbitrary scale used to show the magnitude of viscosity changes in lubricating oils with changes in temperature. Oils with low VI number such as VI=0 ("zero") have high dependence of viscosity change on temperature. They thicken quickly with decreasing temperature, and thin out quickly with increasing temperature. Oils with high VI number such as VI=200, will still thicken with decreasing temperature but not as rapidly, and also will thin out with increasing temperature, but again not as much as low VI oil.
    VI number can also be "negative".
    However, VI does not tell the whole story -- it only reflects the viscosity/temperature relationship between temperatures of 40°C and 100°C. Two lubricants or base oils with the same VI number may perform dramatically different at low temperatures in the -5°C to - 50°C range.
    some some other info I ran across:
    No matter what oil you use for any purpose the ideal viscosity that provides the ultimate lubrication, that is TOTAL bearing surface separation, and at MINIMUM power that is consumed by the lubricants viscosity (MINIMUM TEMPERATURE RISE) occurs ONLY at ONE combination of:
    SPEED
    LOAD
    TEMPERATURE.
    Under ALL other combinations of the three factors, the lubricant is NOT IDEAL.
    Some lubricants, due to much higher than normal viscosity index, can have more advantageous performance over much wider range of TEMPERATURE, SPEED and LOAD, than others and therefore can be used more universally in wide range of applications.
    That is why some lubricants such as single grade SAE 30, must be changed to SAE 20 when operating temperature is reduced or to SAE 40 or SAE 50 when the operating temperature is increased.
    So thicker more viscous oil is needed when engine is operated at higher temperature such as high summer heat.
    Similarly the proper viscosity depends on LOAD, the higher the load the thicker or higher SAE number is required. So on highly loaded engine designed to used SAE 30 oil under normal operation SAE 40 or SAE 50 should be utilized.
    Speed however has the opposite effect, when engine designed to run at 2,000 RPM is constantly run at 6,000 RPM but at the same load, the SAE 30 oil should be substituted with SAE 20 oil. Higher operating speed requires thinner or lower viscosity lubricant.
    It is possible in some applications that the increase in load can be just offset by the increase in speed and then the same oil such as SAE 30 that is just right for NORMAL operation will be also JUST RIGHT for the new HIGH LOAD and HIGH SPEED regime.
    "Old" truckers are well aware of this from experience, they get much better and longer engine life when running in lower gear up-hill. Extra LOAD is imposed on the engine by climbing uphill (lifting cargo weight against the pull of gravity requires more power therefore the engine LOAD is increased), this can be balanced by running engine at much higher RPM (this requires thinner lubricant).
    The alternative of running uphill in low gear, that is at slow engine speed and increased load would surely require increase in motor oil viscosity or else almost certain engine damage would result.
    It would be rather inconvenient to change motor oil before and after every major hill on the Interstate. Therefore changing gears is much more feasible.
    Thinner motor oils such as 5W-20 or even 0W-20 are becoming more popular these days and are even specified by some OEM's (FORD & HONDA) on new 2001 cars.
    Although these oils are promoted as "energy conserving" they generally trade a gain of less than 0.1 MPG in Corporate Average Fuel Economy (CAFE) for shorter useful engine life.
    FORD which has previously designed cars to have 10 year or 150,000 miles life has reduced the mileage life expectation to "beyond 100,000 miles" on vehicles that are operated on SAE 5W-20 Motor Oil.
    HONDA only claims "useful life" as 7-years or 70,000 miles in EPA certifications for their CIVIC which uses SAE 5W-20 Motor Oil, while the previous model that utilized SAE 5W-30 Motor Oil was certified for 10 year or 100,000 mile durability.
    Since both HONDA and FORD Warranty their NEW cars for ONLY 3-years or 36,000-miles the reduction in engine life expectancy is not a factor.
    By contrast Mercedes-Benz recommends use of ONLY Synthetic Motor Oil that is at least SAE 5W-40! This is a recent increase in recommended viscosity from SAE 5W-30. Apparently customer research indicated that engine longevity is more important to typical MB customer than fuel economy.
     
  2. Dennis Nicholls

    Dennis Nicholls Lead Actor

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    So Henry, are you a tribologist? I always looked askance at the use of 5W-20 in my new Ford truck. Even 5W-30 looks pretty thin to me. But this topic has been hashed over and over to no clear conclusion over at the F-150 forum.
     
  3. Clinton McClure

    Clinton McClure Casual Enthusiast
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    I've always used 5W30 in all my cars and suffered no ill effects. I traded in my 93 Cavilier (with 129,000 miles) as well as my 97 Sunfire (with 98,000) and both ran as good the day I traded them as the day I bought them. Neither leaked oil or had any major mechanical problems. I firmly believe it isn't what brand of oil you use, or so much even the weight, but it's how well you take care of your car and perform regularly scheduled mantainence. Right now my 2000 Celica is at 65,500 miles and presents no worries. I well expect to see 300,000 or maybe even 400,000 miles out of her before I have to replace the engine.
     
  4. Todd Hochard

    Todd Hochard Cinematographer

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    Even though my Acura recommends 5W-20, I use 5W-30. But, I use synthetic. I like the extra protection it offers- it pours better, and the valvetrain is quieter. In fact, in my old Z28, the valvetrain quieted WAY WAY down, when I switched from 10W-30 conventional to 10W-30 synthetic. It even surprised me.

    40 weight seems too heavy for today's tight tolerances. I've no data to back that up, other than a few extra seconds of ticking on startup (due to lack of top-end oiling for a few more seconds than normal). Actually, I just thought of one other anecdote- on my '93 Z28 (traded long ago), when I ran it to redline, the oil pressure would start to drop above 5000rpm (pump cavitation, I assume). When I switched to a lighter weight synthetic, that stopped.

    Todd
     
  5. Henry Carmona

    Henry Carmona Screenwriter

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    I think ill be switching to 5W-30 [​IMG]
    On the 10W-40 discussion--
    Citgo says, " General Motors, Ford, Chrysler and most import manufacturers have not recommended this grade for several years. An SAE 20W-50-grade oil won't flow fast enough to give good lubrication in cold weather, particularly at start-up. Also, neither SAE 20W-50 or SAE 10W-40 oils are energy conserving. Most auto manufacturers recommend an SAE 5W-30 or SAE SW-20 grade for new cars, but check and follow your owner's manual."
    I ran accross an article that stated:
    "Very few manufactures recommend 10W-40 any more, and some threaten to void warranties if it is used. It was not included in this article for that reason. 20W-50 is the same 30 point spread, but because it starts with a heavier base it requires less viscosity index improvers (polymers) to do the job. AMSOIL can formulate their 10W-30 and 15W-40 with no viscosity index improvers but uses some in the 10W-40 and 5W-30. Mobil 1 uses no viscosity improvers in their 5W-30, and I assume the new 10W-30. Follow your manufacturer's recommendations as to which weights are appropriate for your vehicle. "
    Choosing Multi Viscosity Oils
    Choosing the most suitable oil for your climate zone is very important also. A heavy base oil would turn to jelly in cold temperatures if some polymers are not added. To prevent this, multi viscosity oils are produced by adding some polymers to a lighter base, thus these oils are thin enough to work at cold temperatures, and safe enough to work at high temperatures. At cold temperatures the polymers are coiled up and allow the oil to flow as the low number indicate (like in 5W-30). As the oil warms up the polymers begin to unwind into long chains and prevent the oil from thinning. Thus, a 5W base oil doesn't thin more than a 30 weight would when it is hot. This is like using two different oils, one for winter and one for summer in one. In the winter base your choice must be the lowest temperature you expect, and in the summer base the highest. The narrowest span with a more heavy base is better if your temperature zone allows, cause a wide span means more polymers, and more polymers are not good for your engine.
    10W-30 or 10W-40?
    10W-30 has a narrower span than 10W-40, thus requires few polymers. 10W-40 requires more polymers than 10W-30 to work at hot temp.
    10W-40 or 20W-50?
    10W-40 has the same 30 point spread with 20W-50, but 20W-50 needs less polymers than 10w-40. Besides this, use 20W-50 only if your temp. zone allows. Look at the chart below
    If lowest expected outdoor temperature is Typical SAE viscosity grades for passanger cars
    0 degrees Celcius (32F)..........................................5W-30 10W-30 10W-40 20W-50
    -18 C (0F).............................................. ...................5W-30 10W-30 10W-40
    below -18 C................................................. ...........5W-30
    Also look for API Service "SJ" mark, that means the oil can be used in all automotive engines currently in use. Some manufacturers use no polymers in some of their products to obtain that viscosity. That means if you go out and buy a 5W-30 Mobil1 that can cost you much, but you must know that it doesn't contain any polymers that can form deposits to obtain that range of viscosity.
    Another automotive newsletter:
    The SAE 10W-40 has not been recommended for use by General Motors Corp. for more than 20 years! This is because the viscosity index (VI) improvers that make an oil have a broad viscosity can breakdown and create engine problems, such as stuck piston rings.
     
  6. Sean Conklin

    Sean Conklin Screenwriter

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    I run fairly loose tolerances in my V-8 Hot Rod, and I use 10W-40. I get slightly better oil pressure at higher RPM's and better idle pressure than with lighter oils.
     
  7. ShaneH

    ShaneH Stunt Coordinator

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    What is the real difference between 5W30 and 10W30, a wider range of operating temperature? I always assumed 5W30 in the winter and 10W30 in the summer was the way to go, is this wrong?
     
  8. Sean Conklin

    Sean Conklin Screenwriter

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    5W30 is lighter in colder temperatures, and flows better on start up in cold weather. 5Winter30.
     
  9. Henry Carmona

    Henry Carmona Screenwriter

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    Shane,
    Im thinking the same.
    I intend to do the exact same thing with my truck.
     
  10. Todd Hochard

    Todd Hochard Cinematographer

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    In the COLD winters of the North, my rules would be:
    For cars 95 and newer:
    0W-30 in winter
    5W-30 in summer
    Older cars
    5W-30 in winter
    10W-30 in summer
    In the South-
    For cars 95 and newer:
    5W-30 year round, but 10W-30 in summer for you hot rodders.[​IMG]
    Older cars
    10W-30 year round
    Exception- my limited experience is that the big Ford and Chevy motors like a slightly heavier oil (5W in the place of 0W, 10W in the place of 5W). And, the Hondas I've run don't seem to like 10W at any time.
    Todd
     

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