Mitch, thank you for you dedication to aquiring data
Ambient temperature vs. engine temperature
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True, but according to ILSAC/OIL chairman Bob Olree of General Motor..."the Sequence IIIG test will play an important role in ensuring GF-4 oils provide adequate wear protection...I want to point out that along with the IVA, the IIIG is a GF-4 wear test."
I think the point is that running the test engine for a 100 hours at 2/3 power levels with 150C oil temps, and oil as thin as 5w20, if the bearings were failing, they'd know about it.
How many people get their 5w20 oil temps up to 302F for an extended period of time, if ever? And if they have an oil cooler, Tony Soprano would probably say, "forget about it".
Bada Bing, Bada Boom!
I added a thermostatically controlled cooler on the Nissan that had the oil temp gauge and what you say is correct.
One other thing I don't think anyone else mentioned was temps vs. oil viscosity and type. For instance, on the aforementioned vehicle I noticed Rotella T 5W-40 would come up to temp faster and run slighter hotter than M1 10W-30 in similar conditions.
I didn't try a wide variety of oils in that vehicle to see the differences but now I wish I would have...
It's not the heat, it's the humidity.
Let's digress a bit here Big Dave,quote:
Originally posted by Big O Dave:
1911, I might add that since a lot of those charts were published, oil has gotten a LOT better, and no longer do you have to run such high viscosities to protect against wear caused by oil thinning out.
Point A) First of all, we're not talking way back in the stone ages, some new cars in the U.S. may still have these charts and many of them that do not now had them just a couple of years ago with the same exact engines.
Point B) If the oil gets thin enough due to temperature rise, you will eventually reach a point where you lose full film lubrication and you can lose it regardless of the quality of the basestocks and additive package. The manufacturers prefer to have bearing inlet viscosities of about 10 to 18 centistokes for each bearing depending on the bearing characteristic number which is a function of load and relative part velocity (linearly related to RPM for a bearing). For the valvetrain, they would prefer much much thicker lubricants to achieve full film lubrication (such that hardening the parts would not be necessary).
C) Listen up here folks cause this one is generally not known for some reason. Babitted jounal or sleeve bearings are always designed with hydrodynamic lubrication in mind. IN other words, aside from corrosion inhibition, they are not designed to be protected by the additives as many BITOGer's ***-ume. Other than having studied this in college, this should be obvious in their construction. They are made of soft very low melting temperature materials that will not tolerate even partial or intermittent contact from a steel shaft very well.
Another thing that seems to be relatively unknown is that mechanical devices that use journal bearings but do not have a valvetrain do not utilize lubricants full of anti-wear; friction reduction, and EP type additives!!! IN fact they generally have about none!!! There are about 18,000 industrial gas turbines in the world that have jounal bearings and their lube additive packages are of the R&O variety or rust and oxidation package variety. There is something to be learned from that fact for many here. Gear and motor oil have many additives that are geared towards (no pun intended) mixed and/or boundary type lubrication scenarios. In your car, these additives are for the valvetrain, timing chain, and maybe help out at the top and bottom of the cylinder strokes where the low velocity is not good. Some of the AW additives may help the journal bearings at start-up somewhat but if you have to depend on them in the absense of a primarily thick film oil wedge for the long term when the motor is hot, your engine is done..........kaput!!!! So let's knock off the nonsense about new additive packages that were not around 3 years ago allowing us to safely run with bearing inlet viscosities of 3 centistokes, that's BS.
IN fact, maybe the chemists here can tell us if most off the shelf oils even have better packages than they did 5 years ago. They worked great back then and had more ZDDP. Maybe some of the add packs are even worse now with teh SM rules? I however have no doubt that the evolution of the API specifications generally demands improved basestocks. This may be where most of the real improvements are occurring.
1911
1911 - this paper tends to confirm everything you just wrote:
http://www.iantaylor.org.uk/papers/Esslingen1998.pdf
and i bet quite a few more where that came from.
http://www.iantaylor.org.uk/papers/Esslingen1998.pdf
and i bet quite a few more where that came from.
An even more interesting paper with germain info:
http://www.iantaylor.org.uk/papers/LL1998.pdf
note that at 0 deg position of conn. rod that all three oil weights have similar film thickness above 100 deg C.
http://www.iantaylor.org.uk/papers/LL1998.pdf
note that at 0 deg position of conn. rod that all three oil weights have similar film thickness above 100 deg C.
Those papers tend to confirm what I wrote. As oils (basestocks, in particular) have gotten better, the need for using higher viscosity oils to protect against "thinning down" with heat has diminished.
Witness the performance of 5W-20 in the above-referenced reports. While the viscosity IS thinner within the bearings (compared to 15W-40) is is STILL more than thick enough to provide the necessary protection.
I stand by my statement: as oils have improved, the need to run higher viscosity oils in order to offset thinning due to high temperatures has diminished.
And, I wasn't talking about additive packages, I was talking about basestocks, when I was referring to improvements in oil. It has just been over the last 6-8 years where hydrocracked basestocks have become prevalent, and they are MUCH better than solvent-refined basestocks, having much higher native viscosity indices.
Witness the performance of 5W-20 in the above-referenced reports. While the viscosity IS thinner within the bearings (compared to 15W-40) is is STILL more than thick enough to provide the necessary protection.
I stand by my statement: as oils have improved, the need to run higher viscosity oils in order to offset thinning due to high temperatures has diminished.
And, I wasn't talking about additive packages, I was talking about basestocks, when I was referring to improvements in oil. It has just been over the last 6-8 years where hydrocracked basestocks have become prevalent, and they are MUCH better than solvent-refined basestocks, having much higher native viscosity indices.
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Again, my good friend (1911), where are the massive failures? Sure all that you say is "correct" ..but where is the proof in the massive folly of 5w-20 use??
The proof isn't in the pudding (remember that cow and horse?).
Are people, in their mass herding stupidity, just subject to blind dumb luck??
*btw- I'm a "heavier when proven to be needed type" oil user.
The proof isn't in the pudding (remember that cow and horse?).
*btw- I'm a "heavier when proven to be needed type" oil user.
Me, too.
I use Rotella-T "Synthetic" 5W-40 in my '83 F250 with a 460. It runs REALLY smoothly on that, and the oil pressure is just slightly on the high side of the center of the guage (no numerical values on stock guage
OTOH, I have been using 5W-30 in my wife's '95 Explorer and my '76 C20 with a 350, but after I'm done ARXing them, I'm gonna let the Elves take over, and run GC in those two.
In my daughter's '05 Focus, it's Pennzoil 5W-20.
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This is surely true. There's a reason that they call them cattle chutes. :wink:
But that doesn't discount the fact that lighter oils, of proper composition, can deliver excellent results in a broad range of climates. They are closer to the lower end of the envelope ..but appear to be sturdy enough to perform that task at hand without undue, or unacceptable, "loss of use".
Mitch Alsup - Very interesting chart!
Not what I would have expected.
Not what I would have expected.
Just remember, this car is built to run at top speeds (180MPH) for as long as the gas tank (or traffic) allows--that is the oil radiator (12"*17") is 1/2 the size of the water radiators (2).
In the heat of Texas summers (105dF in the shade) and at a road race track (TWS) and running the snot out of it (within 3 seconds of TWS lap record for street tires) the oil (5W-40) stabilizes at 265dF.
Hey Guys,
There may be some misunderstanding here, I use 5W-20 in my Mazda 3i for the colder half of the year and would use it year round in any climate in just about any car if my trips were under 8 to 10 miles. I'd run it year round if it were not 100F here in the summer. I run 5W-30 in the summer and would not hesitate to run 10W-40 if my trips were much longer here.
When have I ever said that it was a bad choice at all for many of the engines that specify it? The science says clearly that it all comes down to oil temperatures folks. The science also says that you will experience more wear with a 10 centistoke lubricant at a bearing than a 15 centistoke lube (see Molakule's posts about this). Those of you running very high oil temperatures as a result of your driving style and climate will certainly see more engine wear but perhaps not enough more to be that significant. In more extreme cases, ie SCCA racing in hot climates (some jabronies approach this on the street), very high wear or even failure could even result from loss of hydrodynamic film formation at the bearings. The guys on this board with the oil temperature gauges are the smart ones. As I said, bearing engineers cringe at the thought of 3.5 centistoke oil going into already hot highly loaded bearings. With an accurate oil temperature gauge, you can tell your viscosity.
It's also interesting to note that in the summer here, even though I just have several four way stops on a 17 mile drive with no idling for more than 10 seconds or so, I notice that my cooling fan is on when I shut off the car. This does not happen unless it's about 100F out.
There may be some misunderstanding here, I use 5W-20 in my Mazda 3i for the colder half of the year and would use it year round in any climate in just about any car if my trips were under 8 to 10 miles. I'd run it year round if it were not 100F here in the summer. I run 5W-30 in the summer and would not hesitate to run 10W-40 if my trips were much longer here.
When have I ever said that it was a bad choice at all for many of the engines that specify it? The science says clearly that it all comes down to oil temperatures folks. The science also says that you will experience more wear with a 10 centistoke lubricant at a bearing than a 15 centistoke lube (see Molakule's posts about this). Those of you running very high oil temperatures as a result of your driving style and climate will certainly see more engine wear but perhaps not enough more to be that significant. In more extreme cases, ie SCCA racing in hot climates (some jabronies approach this on the street), very high wear or even failure could even result from loss of hydrodynamic film formation at the bearings. The guys on this board with the oil temperature gauges are the smart ones. As I said, bearing engineers cringe at the thought of 3.5 centistoke oil going into already hot highly loaded bearings. With an accurate oil temperature gauge, you can tell your viscosity.
It's also interesting to note that in the summer here, even though I just have several four way stops on a 17 mile drive with no idling for more than 10 seconds or so, I notice that my cooling fan is on when I shut off the car. This does not happen unless it's about 100F out.
Dave, I agree with you but regardless of how high quality your basestock is, the viscosity drops with temperature and if you get it hot enough (thin enough), you reach a point where wear rates begin to increase and then if you keep going, you ultimately reach a point of engine failure. That's why Nextel Cups cars have oil coolers depsite using awesome basestocks. A quality 20wt basestock is no more viscous than a crappy 20wt basetock at 300F.
We're on the same page, 1911! Concur.
Patman you engine is loafing at 70 just think of the difference if you cruised at 125 + mph.
"Again, my good friend (1911), where are the massive failures? Sure all that you say is "correct" ..but where is the proof in the massive folly of 5w-20 use??"
5W20 seems to be fine for almost everyone in the US. At the international driving style dinner table the US eats mainly milk toast :^)
5W20 seems to be fine for almost everyone in the US. At the international driving style dinner table the US eats mainly milk toast :^)
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