Proof that thiner oils decrease startup wear?

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We often hear that most engine wear occurs at startup when the oil is too thick to lubricate properly. It cannot flow and therefore cannot lubricate. This a motto of some oil companies advertising synthetic oils. My literature review clearly confirms the concept of startup wear. That has been documented by numerous scientists and seems to correlate with low oil and coolant temp. Some evidence points to chemical nature of such wear. It is also clear that low viscosity and/or synthetic lubricants can increase fuel efficiency (by modest amounts, 2% across the board) while not increasing wear by a significant measure (speaking pragmatically, not statistically). Now, did anyone come across an empiric and scientific study showing decreased start up wear with either synthetic or lower viscosity lubricant? Is this a fact or just a myth? Please, no "feels like it should" or "has to" statements.
 
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If you're talking about the initial starting event, I do recall one diesel study that showed measured decreased wear with lower viscosity oil. It, like most published papers, proved what it set out to. It doesn't get any love since start up wear in a diesel is so low compared to its long term steady state wear in the gross numbers.
 
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There's also the paper that states a mono 30wt showed less cold wear than a 10w and 10w-30. There's the more recent one that showed a thicker oil can protect bearings better in a hot restart.
 
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 Originally Posted By: Gary Allan
If you're talking about the initial starting event, I do recall one diesel study that showed measured decreased wear with lower viscosity oil. It, like most published papers, proved what it set out to. It doesn't get any love since start up wear in a diesel is so low compared to its long term steady state wear in the gross numbers.
Diesel fuel has some nice lubrication properties which certainly reduces start up wear too, plus their build like a brick tshit house.
 

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 Originally Posted By: Pete591
http://www.carcraft.com/techarticles/synthetic_vs_conventional_oil/index.html Might be helpful.
Interesting read. While again, we hear:
 Quote:
"Racers also know that most engine wear occurs at start-up, so it's critical that engine parts receive proper lubrication as soon as possible--hence the need for an initially thinner, so-called "winter" viscosity.
But, there is no experiment to prove or disprove that. The study was done with oil temperature at 210 degrees F and showed improvement in torque with 0W30 Mobil 1. Interestingly:
 Quote:
According to 76 Lubricants, most NASCAR teams use the really thin stuff during qualifying, moving up to 20W-50 during the long race (although it's rumored some teams may use the extreme cold-weather thin oils all the time, but don't want to admit to their latest performance "trick").
 
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 Originally Posted By: friendly_jacek
We often hear that most engine wear occurs at startup when the oil is too thick to lubricate properly. It cannot flow and therefore cannot lubricate.
I think that isn't exactly correct. I do know that for any specific bearing load, there is only one optimal combination of viscosity, temperature and pressure. While the lower vis oil is closer to the optimal viscosity for the lower temperature, it's not true that higher vis oil "can't flow" at that temperature, it's just farther away from optimal viscosity for the lower temp condition. Anyway, that's why multi-grades were developed to make the oils viscosity vary to stay closer to the sweet spot over the full temp range.
 
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 Originally Posted By: friendly_jacek
 Originally Posted By: Pete591
http://www.carcraft.com/techarticles/synthetic_vs_conventional_oil/index.html Might be helpful.
Interesting read. While again, we hear:
 Quote:
"Racers also know that most engine wear occurs at start-up, so it's critical that engine parts receive proper lubrication as soon as possible--hence the need for an initially thinner, so-called "winter" viscosity.
But, there is no experiment to prove or disprove that. The study was done with oil temperature at 210 degrees F and showed improvement in torque with 0W30 Mobil 1. Interestingly:
 Quote:
According to 76 Lubricants, most NASCAR teams use the really thin stuff during qualifying, moving up to 20W-50 during the long race (although it's rumored some teams may use the extreme cold-weather thin oils all the time, but don't want to admit to their latest performance "trick").
FYI, if a racing team like a NASCAR team says they believe/know something but you don't see the study/evidence, get over yourself. Those teams spend hundreds of thousands of dollars every year doing in house R&D on EVERY aspect of their cars. They will not just provide you, nor their competition, their knowledge for free. They aren't just making anything up, either. They can't afford to guess wrong.
 
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Ford already proved this, maybe 20 years ago. That's why they started recommending 5w30 all year, instead of 10w30. Probably all of the automakers have run their own tests to confirm. My owners manual in the GM Chevy Venture says ONLY use 5w30, do NOT use a heavier grade of oil.
 
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 Originally Posted By: Captain_Klink
Ford already proved this, maybe 20 years ago. That's why they started recommending 5w30 all year, instead of 10w30. Probably all of the automakers have run their own tests to confirm. My owners manual in the GM Chevy Venture says ONLY use 5w30, do NOT use a heavier grade of oil.
You've got to take it with a grain of salt. There are climates where a 15w-40 will be thinner than a 5w-30 will be in others. One of my biggest problems with the 20wts is the corresponding dumbed down manual with 5w-20 for all climates. If a 5w-20 works well in Canada, a 10w-30 will work just as well in Phoenix.
 
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 Originally Posted By: BuickGN
 Originally Posted By: Captain_Klink
Ford already proved this, maybe 20 years ago. That's why they started recommending 5w30 all year, instead of 10w30. Probably all of the automakers have run their own tests to confirm. My owners manual in the GM Chevy Venture says ONLY use 5w30, do NOT use a heavier grade of oil.
You've got to take it with a grain of salt. There are climates where a 15w-40 will be thinner than a 5w-30 will be in others. One of my biggest problems with the 20wts is the corresponding dumbed down manual with 5w-20 for all climates. If a 5w-20 works well in Canada, a 10w-30 will work just as well in Phoenix.
..but it's a double edged sword, BGN. People often point to spec's outside the US ..but from Canada to the panhandle ..we just about cover it all ..and all spec what they spec (typically 5w-20) ..but for that matter, I imagine 5w-20 @ -30f is thicker than SAE 50 weight @ 85F
 

friendly_jacek

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 Originally Posted By: Captain_Klink
Ford already proved this, maybe 20 years ago. That's why they started recommending 5w30 all year, instead of 10w30. Probably all of the automakers have run their own tests to confirm. My owners manual in the GM Chevy Venture says ONLY use 5w30, do NOT use a heavier grade of oil.
Do we know if they did that for start up wear or rather ease of start in subzero temps and fuel efficiency? Didn't CAFE start in 70'? My cars' manuals also states ONLY 5W30, yet manuals in Europe give a choice from 5W30 to 20W50 for the same car and engine. Aren't car makers concerned about startup wear in Europe?
 
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One thing to remember is the Ford 5w20 spec doubles many of the requirements that the older 5w30 oils had to meet. So hot, cold, or in-between, the newer 5w20 oils seem to stand up very well. Europeans frequently drive at much higher speeds and extend oil change intervals far beyond what most Americans would be comfortable with. One of the reasons for a higher inital viscosity. Ford 5w20 spec... http://www.ilma.org/resources/ford_2004_my.pdf
 
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I think all that startup wear stuff is a bunch of nonsense. The US only recommends thin oils for gas mileage purposes. The US is probably one of the most strict countries when it comes to fuel conservation. You know where you can go on those oil company websites and put in your car`s info and they`ll recommend an oil? Well,the US ones always tell me to use a 10W30 on my car and nothing else. The Australian ones will tell me to go no thinner than a 15W40 and recommend I use a 20W50. When I emailed Mobil awhile back about recommended oil,I got the automated *10W30* response. When I emailed Royal Purple,I actually got an email from a human being telling me to use either their 15W40 or their 20W50 and not the instant "hit the 10W30" button.
 
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 Originally Posted By: friendly_jacek
 Originally Posted By: Captain_Klink
Ford already proved this, maybe 20 years ago. That's why they started recommending 5w30 all year, instead of 10w30. Probably all of the automakers have run their own tests to confirm. My owners manual in the GM Chevy Venture says ONLY use 5w30, do NOT use a heavier grade of oil.
Didn't CAFE start in 70'?
1975 Shortly after was when 5w-30 oils came into wider distribution.
 
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 Originally Posted By: aquariuscsm
You know where you can go on those oil company websites and put in your car`s info and they`ll recommend an oil? Well,the US ones always tell me to use a 10W30 on my car and nothing else. The Australian ones will tell me to go no thinner than a 15W40 and recommend I use a 20W50.
in the miata club, several of us went to the AUS club members and got a copies of manuals from a couple of different years. there were some interesting things that we noticed. for operation in ambient temps from 0c to 100c, the graphic (standard vis bars) showed that you could use anything from 5w20 to 20w50 (including the very puzzling 20w20). note that these recommendations were for API SL or earlier and GFII or III oils. this graphic actually shows much thinner oils (and thicker) than the originally recommended 10w30 in the US (later 5w30). for actual data, i have done OAs on my miata several times, using both 0w40 and 0w20. there was very little difference in the wear metals in a 10k run, although the 0w20 did use 2qts of oil over the 10k run (i only topped up one to keep the sample relatively pristine). the 0w20 run also included 2 trips to texas during 105+ days on the interstate (which were outside of the temperature recommendations of the graph). the earlier miatas, however, give a fine example of why thinner oils decrease startup wear. NA miatas (1990-1997US)use hydraulic lifters which give HLA startup clatter until lubrication reaches them. using 10w30 in colder weather will result in startup clatter for 90 seconds or more. the 0w oils drop this number to 10-15 seconds.
 
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 Originally Posted By: cheetahdriver
in the miata club, several of us went to the AUS club members and got a copies of manuals from a couple of different years. there were some interesting things that we noticed. for operation in ambient temps from 0c to 100c,
That's hotter than Texas.
 Quote:
the graphic (standard vis bars) showed that you could use anything from 5w20 to 20w50 (including the very puzzling 20w20).
SAE 20 only controls normal viscosity at 100C and HTHS at 150C, viscosity's not controlled below 100C. When the 20W is added, then a low temp viscosity range is also specified.
 
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 Originally Posted By: XS650
SAE 20 only controls normal viscosity at 100C and HTHS at 150C, viscosity's not controlled below 100C. When the 20W is added, then a low temp viscosity range is also specified.
interesting and quite good explanation, the 20w20 had baffled me. of course, i mixed my units in the first explanation, try 32-100F. pretty bad for an engineer that yells at folks for not doing dimensional analysis on problems. i plead lack of caffeine.
 
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BuickGN has a very good conclusion. And there is no question that the faster flow and pressure gets to bearings at start up, the better it is for parts. I have seen dramatic differences going from thick to medium oils at start up with a pressure gauge that was at the end of the food chain [far from the pump].
 
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