Attn thick oil guys,20W50 vs 10W40 film strength.

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As we all know,I`m a member of the thick oil group here. I drive my car fast and hard,the way it was designed to be driven,but I`m still very meticulous and careful with it. It`s never raced or abused,I just don`t granny drive it. Fellow Texans know if you regularly drive on I-35,80mph is the nominal average cruising speed if you don`t want to get run over. As per Z32 fsm,10W40-20W50 is recommended if the car is driven fast,raced,or in driven in hot climates,and 10W30 is recommended for fuel economy only. How well will 10W40 protect the engine vs 20W50 under said conditions?
 
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My personal opinion, M1 15W-50 would be an excellent choice. It has a 40C cSt of 131.2 and a 100C cSt of 18.1. It has an HTHS of 4.5. It has a 1200 PPM ZDDP content, an excellent add package complete with FM. My family is spread from North Carolina to extreme northern Virginia. Since 1990, we have around 2,000,000 miles with nothing but Mobil 1 15W-50. This includes small 1.5L in-line 4's to large VA truck engines. Never a problem of any kind and even with so many various types and brands of vehicles there has never been an oil leak, seep, no consumption, and no hard starts even in northern Virginia.
 
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I'd use a synthetic or a syn-blend if I were going that "thick." I doubt you'd hurt your engine whether you used thicker oils in winter or thinner oils in summer in Texas. That being said I also used thicker oil when called for in my 1988 Mazda (10W-40 was 'preferred' all climate, and 15W-40/20W-50 were okay to use in very hot (summer) climates. So I did. In any case, I'd use MaxLife blend 20W-50, which has a nice pour point of -33C and a good CCS. Or the previously mentioned Mobil1 or Pennzoil Platinum 15W-50 would also work well. Amsoil also makes a nice 20W-50 syn. If you don't want to use syn, I'd split the difference and seriously consider using a HDEO like Chevron or Shell Rotella 15W-40...
 
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Judging from the experiences both you and 'BuickGN' have had with conventional 20W-50's, I'd just stick with that. It does have its uses, and yours seem to be it.
 
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All I can say is that my experience with 20w50 was very BAD. Granted, it was an old engine (1966 Chrysler 383 with over 250,000 miles at the time) and I tried M1 20w50 to reduce oil consumption, but the result really put me off "thick" oils. Oil consumption shot *up*, pinging and detonation went out of control, and the plugs started to foul (they'd never done that on 10w30). I went back to 10w30 and all was right with the world again. If I still had that engine in service, I'd be really tempted to throw some 0w20 at it just to see what would happen. That said, I've often posted how much I like RTS 5w40. For certain applications, it just about can't be beat. I wouldn't say that I'm in the "thin oil" camp, but I do prefer setting an engine up for high oil *flow*- looser clearances and/or full-grooved bearings combined with a high-volume oil pump and a moderate thickness of oil. I don't like trading reduced flow for higher pressure because flow = cooling. I'm a fellow Texas driver (BTW- I-35 has nothing on I-10 west of Junction where the speed limit is 80 and the average cruising speed is well over that...) and I think that its hot enough here that a lot of engines will see a difference in deposit formation with synthetics vs conventional oils, even if they're not pounded quite that hard.
 

aquariuscsm

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 Originally Posted By: 440Magnum
All I can say is that my experience with 20w50 was very BAD. Granted, it was an old engine (1966 Chrysler 383 with over 250,000 miles at the time) and I tried M1 20w50 to reduce oil consumption, but the result really put me off "thick" oils. Oil consumption shot *up*, pinging and detonation went out of control, and the plugs started to foul (they'd never done that on 10w30). I went back to 10w30 and all was right with the world again. If I still had that engine in service, I'd be really tempted to throw some 0w20 at it just to see what would happen. That said, I've often posted how much I like RTS 5w40. For certain applications, it just about can't be beat. I wouldn't say that I'm in the "thin oil" camp, but I do prefer setting an engine up for high oil *flow*- looser clearances and/or full-grooved bearings combined with a high-volume oil pump and a moderate thickness of oil. I don't like trading reduced flow for higher pressure because flow = cooling. I'm a fellow Texas driver (BTW- I-35 has nothing on I-10 west of Junction where the speed limit is 80 and the average cruising speed is well over that...) and I think that its hot enough here that a lot of engines will see a difference in deposit formation with synthetics vs conventional oils, even if they're not pounded quite that hard.
Is the posted speed limit really 80????? That`s be a trip seeing that sign!
 
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 Originally Posted By: aquariuscsm
Is the posted speed limit really 80????? That`s be a trip seeing that sign!
Nah. I've driven all of I-35 down there, and there's one short stretch in extreme south Texas (approaching Laredo) where the marked speed is 75. Most rural stretches of I-35 are marked 70. You're not going to be driving anywhere near 80 mph on the I-35 stretches through San Antonio or Dallas, and you're lucky to be able to do half that through Austin... Fastest urban driving I saw in Texas was most certainly in Houston.
 
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Yes I10 is posted at 80 mph from Kerrville actually all the way to El Paso. It is pretty cool actually and you can easily run 85-88 past the troopers and they dont seem to mind!
 
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I'd suggest going for the 10W-30 or a better choice ... a 5W or much better a 0W-30. I'd pick a grade that meets the oil's 'average' operating temperature. Something in the middle range.... not the extremes. True, it has to be able to meet the minimum factory recommendation at 221F/100C. A 'multi-grade' with a huge range 5W-X or 0W-X is the far better choice. FWIW, I live in the Hill Country and even on our hottest days and towing a 17' hybrid camper, the oil temperature on my Toyo Sienna's 3.0L V6 does not run hotter than the coolant temperature... about 220F. Not a member of the 'thicker is better' clan I use a 0W-30 year round. Thinking on AEHass' recent thread... I believe that viscosity selection is a moving target. You want the factory recommended viscosity at full operating temperature (212F/100C), i.e., a 30 weight. And below that a so called 'winter' weight that gives you widest range of flow, pumpability & protection at temperatures BELOW the max operating temps.... which is where the oil runs the vast majority of the time. In fact the oil temp is all over the place... always a moving target. Case in point... my Cammy Hybrid. I'm coming to the conclusion that putting in anything but a 0W or 5W-20 is a bad idea. Bad idea indeed. A 20 weight is more than adequate ... over kill really ... the way this engine operates. What it really needs is a 0W or 5W or somewhere between that and the 20 almost all the time. I've never seen the oil temp above 150F/65C even after a fast run on a hot day. Which is why TOYO recommends a 0W-20 as the preferred grade.
 
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This may help from a previous session of posts: Effect of Lubricant Properties and Lubricant Degradation on Piston Ring and Cylinder Bore Wear in a Spark-Ignition Engine, Schneider et al: Let me begin by saying that every person interested in motor oil should go to SAE.org and purchase this article. (The paper was very detailed and I have tried to simplify the results. Also, I will need to report the results in several different postings so hang on please.) This research is made more relevant by actually using V-6 engines for wear testing - 1999 GM 3.4-L 60 degree block. And the radiotracer method of wear detection has been shown to be very accurate. They go on to say that cylinder wear and ring wear are perhaps the best areas to test oil and wear for engine longevity, particularly the rings. Loads and RPMs varied during tests and for most tests the coolant and oils were artificially kept in the normal operating range for the engine. The coolant was not allowed to rise over 203 F and the oil was kept below 248 F. The basic test oil was a fully formulated 5W-30 quality oil. Comparisons were made between SJ GF-2 and SL GF-3 oils, both mineral based and synthetic oils were tested. Mineral based SJ oils were tested with varying quantities of ZDDP. Fully identical mineral based oil additive packaged SJ oils of different viscosities were compared. Wear rates were also tested compared to oil temperature. Wear rates were determined by measuring the radioisotopes in the oil. It was noted that the accumulation in the oil filter was minimal. This shows that metals in the oil are a good way to measure wear. (Note that with cavitation wear the metal particles would be large and caught in the filter as would the larger dirt particles.) Results of comparing GF-2 to GF-3 lubricants: In general, wear rates were high during the start up period (20 minutes) as previously noted (1). Then a steady state of less wear was reached at 2,000 RPM and low load. There was a big increase in wear rate when the load was at wide open throttle, WOT, at 2,000 RPM. A modest increase was noted if you kept the load at WOT and increased the RPM to 4,000. Actual numbers: Average wear (ug/h) for 650 RPM, low load = 50, for 2,000 RPM, low load = 79. For 2,000 RPM at WOT = 516, for 4,000 RPM at WOT = 758. They state that wear is independent of RPM but there is a high correlation between wear and engine load. (This seems odd at first. You double the RPM but the wear does not double as long as the load is the same. The wear rate per revolution actually decreases with RPM. The overall wear may increase but it is less per revolution.) They state that there is little concern for ring wear under typical light load conditions. (Typical city and steady state U.S. highway conditions.) They conclude that there were no differences between the SJ GF-2 and SL GF-3 mineral based oils in wear rates. This is the null hypothesis as the major difference between these oils is the newer lower volatility and increased oxidative stabililty between these oil classes. Part 2: Continuing with SJ GF-2 and SL GF-3 differences they show that there is no significant differences between the oils for the initial break-in wear of top compression rings. They state that bore wear differes from ring wear in that most wear occurs during initial break-in and with start up periods. Steady state wear is very low except when changing to high load conditions. But even here bore wear is less than ring wear rates. They reiterated that start up wear was most significant but there were no differences between the oil classes. They compared the mineral based SJ oils for wear rates by varying the ZDDP levels. There were no differences between phosphorous levels of 0.10 and 0.05. The only other level tested was zero ZDDP where wear rates doubled. Another SAE paper showed no difference in wear as long as the level was greater than 0.03 (2). They further show that there is in fact minimal bore wear differences when no ZDDP is present. (Note that doubling the wear rate is still not too bad as the rate of wear was still relatively low.) They conclude that the newer GF-4 oils will have no negative impact on ring and bore wear rates even with the reduced ZDDP levels. (I heard information that the ZDDP levels will be 0.05 in the GF-5 Oils.) Oil age effects were tested by measuring wear after the oil was subjected to 16,000 miles of city driving. Although the oils thickened some, TAN increased and TBN decreased, there were no differences in wear rates from fresh oil. The test oils were mineral based SJ GF-2. Part 3: Fully formulated Synthetic SJ 0W-30, 5W-30 and SL 0W-30 oils were compared to SJ and SL 5W-30 mineral based oils for wear. There were no differences. (This is worth repeating - there were no differences in wear rates between mineral and synthetic based oils.) Next are the effects of viscosity and oil temperature. Only ring wear was tested as they state it was most sensitive. They compared basic SJ GF-3 mineral oils. The additive packages were the same. The only difference was the viscosity of the base oils. The following grades resulted: 0W-10, 5W-20, 5W-30, 10W-40. The HTHS for these oils were 2.17, 2.83, 3.09 and 3.76. There was no difference in wear rates. The oils were tested at all RPMs and Loads, no difference between oil grades were noted. All the oils had increasing wear rates as the load increased but all increased at the same rate across the board. Most interesting to me was the way they tested wear at lower, start up, oil temperatures. In a previous study (1) they start with room temperature engines and oil showing the trend of decreasing wear as the engine heated up. In the current study they actually took a hot engine and chilled the coolant and oil from that of the normal operating temperature to a coolant temperature of around 80 F and oil temperature to 70 F. As the temperatures fell the wear increased. It reached the same rate of wear as the 4,000 RPM full load WOT. This was with the load at the minimum level. The fluids were then allowed to heat back up to normal operating temperatures and the wear rates normalized (decreased). Wear at room temperature oil was 20 times higher than wear at normal operating temperatures. This finding is what closed the article. They stated that this will be the next focus of their upcoming research. aehaas (1) 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.) (2) 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 valve train 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.)
 
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 Quote:
Case in point... my Cammy Hybrid. I'm coming to the conclusion that putting in anything but a 0W or 5W-20 is a bad idea. Bad idea indeed. A 20 weight is more than adequate ... over kill really ... the way this engine operates. What it really needs is a 0W or 5W or somewhere between that and the 20 almost all the time. I've never seen the oil temp above 150F/65C even after a fast run on a hot day. Which is why TOYO recommends a 0W-20 as the preferred grade.
Unless they had 150F as a target oil temp (if so, that throws some of the hot oil theory out the window- most recommend 180f for full power operations in hi-per applications) ..then you need a 0w-10. I think that they know this too, but aren't ready to revolutionize the market with the expense involved.
 
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 Originally Posted By: AEHaas
This may help from a previous session of posts: Effect of Lubricant Properties and Lubricant Degradation on Piston Ring and Cylinder Bore Wear in a Spark-Ignition Engine, Schneider et al: Let me begin by saying that every person interested in motor oil should go to SAE.org and purchase this article. (The paper was very detailed and I have tried to simplify the results. Also, I will need to report the results in several different postings so hang on please.) This research is made more relevant by actually using V-6 engines for wear testing - 1999 GM 3.4-L 60 degree block. And the radiotracer method of wear detection has been shown to be very accurate. They go on to say that cylinder wear and ring wear are perhaps the best areas to test oil and wear for engine longevity, particularly the rings. Loads and RPMs varied during tests and for most tests the coolant and oils were artificially kept in the normal operating range for the engine. The coolant was not allowed to rise over 203 F and the oil was kept below 248 F. The basic test oil was a fully formulated 5W-30 quality oil. Comparisons were made between SJ GF-2 and SL GF-3 oils, both mineral based and synthetic oils were tested. Mineral based SJ oils were tested with varying quantities of ZDDP. Fully identical mineral based oil additive packaged SJ oils of different viscosities were compared. Wear rates were also tested compared to oil temperature. Wear rates were determined by measuring the radioisotopes in the oil. It was noted that the accumulation in the oil filter was minimal. This shows that metals in the oil are a good way to measure wear. (Note that with cavitation wear the metal particles would be large and caught in the filter as would the larger dirt particles.) Results of comparing GF-2 to GF-3 lubricants: In general, wear rates were high during the start up period (20 minutes) as previously noted (1). Then a steady state of less wear was reached at 2,000 RPM and low load. There was a big increase in wear rate when the load was at wide open throttle, WOT, at 2,000 RPM. A modest increase was noted if you kept the load at WOT and increased the RPM to 4,000. Actual numbers: Average wear (ug/h) for 650 RPM, low load = 50, for 2,000 RPM, low load = 79. For 2,000 RPM at WOT = 516, for 4,000 RPM at WOT = 758. They state that wear is independent of RPM but there is a high correlation between wear and engine load. (This seems odd at first. You double the RPM but the wear does not double as long as the load is the same. The wear rate per revolution actually decreases with RPM. The overall wear may increase but it is less per revolution.) They state that there is little concern for ring wear under typical light load conditions. (Typical city and steady state U.S. highway conditions.) They conclude that there were no differences between the SJ GF-2 and SL GF-3 mineral based oils in wear rates. This is the null hypothesis as the major difference between these oils is the newer lower volatility and increased oxidative stabililty between these oil classes. Part 2: Continuing with SJ GF-2 and SL GF-3 differences they show that there is no significant differences between the oils for the initial break-in wear of top compression rings. They state that bore wear differes from ring wear in that most wear occurs during initial break-in and with start up periods. Steady state wear is very low except when changing to high load conditions. But even here bore wear is less than ring wear rates. They reiterated that start up wear was most significant but there were no differences between the oil classes. They compared the mineral based SJ oils for wear rates by varying the ZDDP levels. There were no differences between phosphorous levels of 0.10 and 0.05. The only other level tested was zero ZDDP where wear rates doubled. Another SAE paper showed no difference in wear as long as the level was greater than 0.03 (2). They further show that there is in fact minimal bore wear differences when no ZDDP is present. (Note that doubling the wear rate is still not too bad as the rate of wear was still relatively low.) They conclude that the newer GF-4 oils will have no negative impact on ring and bore wear rates even with the reduced ZDDP levels. (I heard information that the ZDDP levels will be 0.05 in the GF-5 Oils.) Oil age effects were tested by measuring wear after the oil was subjected to 16,000 miles of city driving. Although the oils thickened some, TAN increased and TBN decreased, there were no differences in wear rates from fresh oil. The test oils were mineral based SJ GF-2. Part 3: Fully formulated Synthetic SJ 0W-30, 5W-30 and SL 0W-30 oils were compared to SJ and SL 5W-30 mineral based oils for wear. There were no differences. (This is worth repeating - there were no differences in wear rates between mineral and synthetic based oils.) Next are the effects of viscosity and oil temperature. Only ring wear was tested as they state it was most sensitive. They compared basic SJ GF-3 mineral oils. The additive packages were the same. The only difference was the viscosity of the base oils. The following grades resulted: 0W-10, 5W-20, 5W-30, 10W-40. The HTHS for these oils were 2.17, 2.83, 3.09 and 3.76. There was no difference in wear rates. The oils were tested at all RPMs and Loads, no difference between oil grades were noted. All the oils had increasing wear rates as the load increased but all increased at the same rate across the board. Most interesting to me was the way they tested wear at lower, start up, oil temperatures. In a previous study (1) they start with room temperature engines and oil showing the trend of decreasing wear as the engine heated up. In the current study they actually took a hot engine and chilled the coolant and oil from that of the normal operating temperature to a coolant temperature of around 80 F and oil temperature to 70 F. As the temperatures fell the wear increased. It reached the same rate of wear as the 4,000 RPM full load WOT. This was with the load at the minimum level. The fluids were then allowed to heat back up to normal operating temperatures and the wear rates normalized (decreased). Wear at room temperature oil was 20 times higher than wear at normal operating temperatures. This finding is what closed the article. They stated that this will be the next focus of their upcoming research. aehaas (1) 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.) (2) 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 valve train 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.)
Thanks for sharing it is very interesting. It also confirms that the guy that lives 5-10 minutes from the freeway, who needs to get on that freeway fast on a cold winter morning, is destroying his engine because the oil hasn't reached operating temperature. This news can be shocking for some of us who are obsessed with their cars lasting forever. It raises the question that for the person who lives near the freeway and finds it difficult to get on w/o nailing it might be better off warming up his engine first, since slow steady acceleration is impossible? It also seems that other than extending OCI's synthetic oils don't offer anything in terms of reducing wear? All good fuel for more debate. AD
 
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One reason I like 0W-XX and lightweight oils in general is because I have sports cars that I like to rev up high early, before they are fully warmed up. Running lighter oils makes me feel more comfortable doing this and used oil analysis supports this. I have no fears of using thinner engine oils than specified for my applications. aehaas
 
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I like the 0W-xx synthetics for that reason too. It doesn't rule out the 20 minute to operating temp guideline, but I bet it helps. AD
 
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 Originally Posted By: aquariuscsm
 Originally Posted By: 440Magnum
I'm a fellow Texas driver (BTW- I-35 has nothing on I-10 west of Junction where the speed limit is 80 and the average cruising speed is well over that...) and I think that its hot enough here that a lot of engines will see a difference in deposit formation with synthetics vs conventional oils, even if they're not pounded quite that hard.
Is the posted speed limit really 80????? That`s be a trip seeing that sign!
Enough of a trip that I have a photo of one of the signs as seen down the hood of my '66 Polara (after removing the tired 383 and putting in a new 440) ;-) I'll see if I can find the picture and throw it on Photobucket, then I'll put a link here later.
 
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 Originally Posted By: AEHaas
One reason I like 0W-XX and lightweight oils in general is because I have sports cars that I like to rev up high early, before they are fully warmed up. Running lighter oils makes me feel more comfortable doing this and used oil analysis supports this. I have no fears of using thinner engine oils than specified for my applications. aehaas
Quite right, Doc!!! I'm a block from a 65mph highway. It's light the fires and gett'r on! NO WORRIES! No matter what I'm driving. No worries at all!!!!
 
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 Originally Posted By: 440Magnum
 Originally Posted By: aquariuscsm
 Originally Posted By: 440Magnum
I'm a fellow Texas driver (BTW- I-35 has nothing on I-10 west of Junction where the speed limit is 80 and the average cruising speed is well over that...) and I think that its hot enough here that a lot of engines will see a difference in deposit formation with synthetics vs conventional oils, even if they're not pounded quite that hard.
Is the posted speed limit really 80????? That`s be a trip seeing that sign!
It's true! It's true!!!!
 
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