Oil just gets thinner, absolute viscosity, when hot.
The 10 and 30 numbers are from old straight-grade oils- you look in the book and know the viscosity for any temperature.
Multi-weight oils don't thin as much with temperature.
The viscosity is less important than you may think (until you get to a won't-crank thickness). If it is a little high, it heats and thins.
There is HIGH pressure inside a loaded rotating bearing. The 40psi is just to move the oil around (specifically through crank arms). Inside a bearing a "wedge" of oil builds to peak pressures over 1,000psi. Oil will thicken at these pressures. The effective viscosity in the wedge is far thicker than you see.
The viscosity does NOT keep the metal from touching. If the bearings were perfectly smooth, the oil pressure *will* build to balance the load. If the bearings are deeply flawed, no oil can prevent contact.
Oil viscosity is largely about how large an oil-pump they want to use and yes, how much parasitic drag is involved in *pumping* thick oil. The friction in the bearings is astonishingly low and only slightly related to viscosity.
We are up to "SN" now? I remember the 1960s, engines would gunk-up their oil. Lost one fine car that way; limped several more with bad but not-yet-fatal bearing slop. It was "SD" and then "SE" oil which made all that GO AWAY (at least for classic US engines). Had a 1979 Windsor which I expected would have gunked oil like all the others, tore it down, clean as a whistle. Had SF oil most of its life.
The 10 and 30 numbers are from old straight-grade oils- you look in the book and know the viscosity for any temperature.
Multi-weight oils don't thin as much with temperature.
The viscosity is less important than you may think (until you get to a won't-crank thickness). If it is a little high, it heats and thins.
There is HIGH pressure inside a loaded rotating bearing. The 40psi is just to move the oil around (specifically through crank arms). Inside a bearing a "wedge" of oil builds to peak pressures over 1,000psi. Oil will thicken at these pressures. The effective viscosity in the wedge is far thicker than you see.
The viscosity does NOT keep the metal from touching. If the bearings were perfectly smooth, the oil pressure *will* build to balance the load. If the bearings are deeply flawed, no oil can prevent contact.
Oil viscosity is largely about how large an oil-pump they want to use and yes, how much parasitic drag is involved in *pumping* thick oil. The friction in the bearings is astonishingly low and only slightly related to viscosity.
We are up to "SN" now? I remember the 1960s, engines would gunk-up their oil. Lost one fine car that way; limped several more with bad but not-yet-fatal bearing slop. It was "SD" and then "SE" oil which made all that GO AWAY (at least for classic US engines). Had a 1979 Windsor which I expected would have gunked oil like all the others, tore it down, clean as a whistle. Had SF oil most of its life.
Oops! Spoke too soon. This thing's a whole lot faster after disabling all the crapware. I did the same thing on my phone when I got it, but I didn't remember it making this much difference. The tablet is much more useable now (save for the charger nonsense).
"Never mind."
- Emily Litella
Not to mention the centrifugal force acting on the oil at the end of a 3 to 4 inch crankshaft arm spinning at a few thousand RPM.
Back in the old days (1950's cars) one would pour a little 90W gear lube into the crank case to quiet a rod bearing that had began to become audible due to wear. Then they invented STP, a super thick slime that kept my old 1949 Plymouth alive with .004'' bearing clearance until one bearing finally spun. Teardown revealed about 1/2 inch thick coating of sludge on every non moving part in the engine, mostly due to the STP. After considerable work with a paint scraper and several cans of Gunk, the block was ready for the hot tank. After 4 days in the tank I still had to scrape and Gunk some more before rebuilding.
The voice of experience can remember that pouring some of that super thick goo into a cold engine and then starting it can shear the tang off the oil pump drive rod requiring some serious engine surgery. The engine in question was a V8 Pontiac, but many other engines had an oil pump drive rod driven from the distributor gear.
Despite some serious beating on the little turbocharged Dodge, there was zero sludge in that engine when I took it apart. I tried several different camshafts in an attempt to find a balance between maximum power and passing the yearly exhaust emission sniffer test. I finally decided that I would swap out the cam every year to pass the sets, then put the good one back in. The cylinder head is a common place for sludge to grow on an OHC engine, but there was none.....Mobil 1 doesn't form sludge.
George, you definitely have knowledge of this stuff from the inside out. I've been using Mobil 1 in my old Nissan for several years now. My main reason for switching from conventional oil is that I was told it was better for cars that aren't driven regularly (mine's an '02 with about 53K miles); that it sticks to the parts better, and so reduces the wear & tear during startup after sitting around. Does this sound plausible, in your experience?
One rather odd thing I've noticed is that this stuff seems to expand & contract a little more than conventional oil? My engine doesn't leak it or burn it, but in cold weather the dipstick will read about 1/8-1/4 qt. lower, then in the springtime it will be back to normal! Weird.
One rather odd thing I've noticed is that this stuff seems to expand & contract a little more than conventional oil? My engine doesn't leak it or burn it, but in cold weather the dipstick will read about 1/8-1/4 qt. lower, then in the springtime it will be back to normal! Weird.
Sludge was mainly caused by leaded gas.
I once, as an interesting project, stripped my engine down and re-bored it in small tool and die shop I worked at.
Underneath a black layer in the sump was thick coating of gray sludge, also the crankshaft oil ways was completely gummed up with the same thick grey sludge. I remember pushing a rod into one end of the crankshaft way and a toothpaste like gray worm exited from the big end journal.
Engines keep so clean now, I'm sure we are changing our oil too frequently.
Since the removal of lead from gas we never hear of big ends knocking and engines last much longer.
I once, as an interesting project, stripped my engine down and re-bored it in small tool and die shop I worked at.
Underneath a black layer in the sump was thick coating of gray sludge, also the crankshaft oil ways was completely gummed up with the same thick grey sludge. I remember pushing a rod into one end of the crankshaft way and a toothpaste like gray worm exited from the big end journal.
Engines keep so clean now, I'm sure we are changing our oil too frequently.
Since the removal of lead from gas we never hear of big ends knocking and engines last much longer.
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Metallurgy, machining, and manufacturing methods have brought us engines with much more exacting dimensional tolerances. That helps control the bearing clearances such that less total clearance is needed. Many "big end" failures were caused by out of roundness or out of tolerance rods, crank journals and bearings to begin with.
The main reasons that engines live so much longer today is fuel injection. The carburetor of yesterday left a lot of fuel unmixed so that droplets coated the cylinder walls letting fuel sit on the rings. This washed the oil off the cylinder walls, and some got past the rings polluting and diluting the engine oil.
A diesel engine has no air valve, and thus takes a full gulp of air on every intake stroke. They run very lean at idle and thus knock. A diesel engine MUST be built to withstand this and is a very stout build. That's why they are so heavy. Remember GM's attempt at putting diesel heads on gas engine blocks in the late 70's. How long did those engines last.......about as long as the Chevy Vega engines with aluminum cylinder walls!
I picked up a clam shell-style chassis at one of the local surplus houses, planning to gut the interior. Lotsa goodies inside, including six 2200uF, 450 computer grade capacitors, a couple of SCR chocolate bar modules on a heat sink, a bitsy TDK SMPS,and a few other odds and ends. Now I have to figure out what I'm sticking in the chassis.
Probably does not affect you.
Apologies for archaic thermometer; your manual has the degrees C.
I just had a total failure of my One+ system.
The old NiCad cells would charge and run in cold. Not as well, but run.
This new Lion system- the charger will not even try to charge below 40 degrees F. And I had a battery in the charger, charged a month ago, but at +6 deg F I got nothing, zero, zilch. Another batt I got whir r r.
Since I already had the ladder set up to prune some snow-sagged branches, I was put-out.
I guess I need to keep the charger and batts in the dining room until spring (perhaps late April).
wow sorry to hear that!
I suppose you could heat the batteries up in front of a heater (electric heater, no flames) before you step outside to do some pruning but the whole idea of using battery powered devices is to reduce emissions. But if you are using energy to heat up a room of your house anyway it shouldn't add anything to overall emissions.
Even if you do use energy to heat the batteries up its still going to end up being less emissions than a petrol powered pruner because the small engines don't have a catalytic converter and they don't burn all of the fuel used.
Just be careful not to melt the battery cases.
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Every time I bring a pound of cold battery into the house, the house drops 0.01 Deg (estimated) and the furnace burns another drop of propane.
I don't believe I am much "reducing emissions" with battery. They have to charge, and here that is mostly gas but we are burning coal too. It is a long way from the generators and if you know the area we must lose a lot in the lines. You put more into the charger than you get out of the battery; fast-charge is significant loss.
I have four corded chainsaws and a rope-start saw. But this is up a ladder! I have done such work but managing a heavy cord with frozen fingers 20 feet up is asking for trouble.
The main use for these ONE+ is carpenters and handymen. Who do work all winter here in Maine. I bet a fair number are grumbling now. As I said, the old NiCad would "work" in cold. These new ones, you really gotta keep them warm. On a jobsite, that may mean leaving the truck running.