Is 'most wear at startup' a myth?

[AEHaas]

There is a gradual increase in oil delivery to the upper engine parts taking several minutes to get even minimal FLOW rates. The pressure may actually be very high.

AW additives are of several types so that there is always one type operating at any given temperature - in current oil formulations.

The viscosity IS too thick at start up. One of the mandates of the SM rated oil is to provide thinner oils for the start up period. This is not meaning for minus 30 degree weather but for normal everyday use at start up.

When oil is too thick for a given RPM a process called cavitation occurs resulting in large chunks of bearing material destruction.

aehaas

 

[Fastride95]

Like others have suggested on here it's not so much the start-up process as it is the fact that most vehicle engines are cold during start-up.

A more accurate wording would be that most engine and most component wear, for that matter, take place during cold operation before the vehicle has reached optimal tempurature.

The fuel system is running slightly rich resulting is higher fuel contamination, there is a temporary absence of optimum film coverage in the top end, the fluids are too thick overall, etc..

I just drive gently for 5 minutes, "normally" after that and avoid running the vehicle hard at all until ~20 minutes of operation. No extensive idling at start-up either. I start the vehicle and it idles just long enough for me to put on my safety belt, put everything in it's place and then I'm in gear driving away.

The only exception was during my time in Alaska. I'd often start the car and it would idle the whole time I was out there swearing and scraping 1/2" or more of ice from the windows. Then again block heaters are the norm out there. Many vehicles came with them stock from the factory or dealership.

 

[John K]

true fact: a redundancy

 

[ruking77]

I think if you take AEHaas's two posts together, the studies cited directly address the tendency of a lot of folks who post on this web site to want to use "other than" specified/oem recommended oil viscosities in their engines, usually thicker. (and some times thinner)

 

[kloppilt]

quote:

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The viscosity IS too thick at start up. One of the mandates of the SM rated oil is to provide thinner oils for the start up period. This is not meaning for minus 30 degree weather but for normal everyday use at start up.

When oil is too thick for a given RPM a process called cavitation occurs resulting in large chunks of bearing material destruction.

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Wouldn't it make sense to make sure that ALL the oils are zero weight at low temperatures? That would prevent oil being TOO thick at startup?

 

[LarryL]

For a pan heater you could try a site sponsor...
Pan heater

And normal temp as mentioned above means oil temp up to normal operating temperature. Coolant is not a good measure of normal. It heats up too quickly.

 

[kloppilt]

Umm, it looks like it's a 110 volt heater. It doesn't say whether the cord remains dangling while you drive or is it unplugged somehow.

 

[Winston]

quote:

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Wouldn't it make sense to make sure that ALL the oils are zero weight at low temperatures? That would prevent oil being TOO thick at startup?

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Well, you have to look at the viscosity of the particular oil you are using, at the temperature that you start up. My start up temperature is rarely lower than 50 deg F (car in garage at night). Here are some viscosities from a chart that was posted in another thread.

code:

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TEMP(C ) TEMP(F) M1 0W-40 GC 0W-30 M1 0W-30 M1 5W-30 M1 10W-30 M1 0W-20 RL 5W-20

10 50 327.6 291.8 231.3 240.1 298.3 188.5 261.8

20 68 192.9 168.8 135.3 138.3 164.1 109.5 144.5

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Note that M1 5W30 is thinner at my startup temperature than GC 0W30. So, 0W oils do not always get you the thinnest oil at startup.

 

[Blue99]

Good Point, Winston!

This is the common "thin oil" myth regarding 0W-30's.

M1 0W-30 and 5W-30 are, for practical purposes, the same viscosity at temps of 32F and higher, where most start-ups are made.

 

[JAG]

Soley blaming wear on the viscosity of oil at start-up is a myth. "Fixing" this issue by using a super low viscosity oil is a myth. Alleviating the problem by using block heaters and pan heaters works. Cold temps inside cylinders is a big part of the problem.

 

[Gary Allan]

Dr. Haas is trying to point out that no oil, currently produced, is at the right viscosity at ambient temp ..any ambient temp. When they develop an oil with near infinite VI that is a 20 weight (or whatever works) @ -40F and is also a 20 weight @ 100C ...then ..and only then will that statement no longer be true. But, in practicality, you've got to compare the statement to one like "no heart or lung has enough capacity for you to run a mile".

Since we're concerned about the highest wear causing part of the event, we don't care as much about the upper end of it. So we should use the lowest 100C visc possible/adaquate ...with the "least thick" cold spec available. For most engines this is a 5w-20 or a 0w-20.

 

[moribundman]

Where exactly does the most significant wear occur during the cold start and during warm-up? In crank bearings, con-rod bearings, cam bearings, cam lobes, rings or cylinders?

 

[Gary Allan]

quote:

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Soley blaming wear on the viscosity of oil at start-up is a myth. "Fixing" this issue by using a super low viscosity oil is a myth.

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Perhaps. There is no "fixing" ..reduction may be possible.

quote:

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Alleviating the problem by using block heaters and pan heaters works.

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Not one bit more than lower viscosity oils. All you are doing with block heaters and pan warmers (mostly) is lowering the viscosity of the oil. It sorta supports the "myth".

quote:

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Cold temps inside cylinders is a big part of the problem.

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Absolutely. The big nut to crack is getting pistons to think that they're experiencing 2500F combustion and expanding like they would. No pan heater or block warmer can do that. They can only simulate the apparent indicators that warmup has occured. I imagine that it's the same for high stress valve trains. They too probably have their own form of "ill fittment" when cold ..but could probably benefit more from the "brief relief" that lower viscs oils provide in colder starting situations.

 

[JAG]

Block heater heats up the combustion chamber surfaces and coolant so there is less condensation of moisture, acids, and unburnt fuel on them that corrodes metal surfaces and "washes" and pollutes the oil layer on cyldinder walls. Those things cause additional damage not seen to that degree at operating temps. Heat from block heater also gradually transfers some heat to the oil both before startup and especially after startup, lowering the viscosity. Some engines have a coolant/oil heat exchanger and in these, the warm coolant would heat up the oil more quickly than otherwise.

Oil pan heater lowers oil viscosity and transfers some heat to the engine after startup (which may make the oil actually decrease in temp but at least that heat is doing good for the engine).

Goal is to get everything just like it's not a cold-start. The closer you get the engine itself, coolant, and/or oil up to temp, the closer the contitions are to not being a cold-start. A cold engine with an oil that has a viscosity that does not vary with temp will still have higher start up wear than same oil used while starting the same warm engine.

 

[LarryL]

Startup wear is from first crank to normal oil temp. Stationary engines that are kept warm with a pan heater that heats the block and coolant are are kept that way for emergency service show a dramatic decrease in wear for engine hours run. With pan heaters, bypass filters and good oil you can get more use from a gen set.

 

[Gary Allan]

quote:

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Block heater heats up the combustion chamber surfaces and coolant so there is less condensation of moisture, acids, and unburnt fuel on them that corrodes metal surfaces and "washes" and pollutes the oil layer on cyldinder walls. Those things cause additional damage not seen to that degree at operating temps.

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Agreed. But you're only shortening the duration of an unavoidable event ..or lessening the impact of it. Now you can virtually eliminate the fuel enrichment cycle ..but in most cases you're simulating a warmer climate start. Not too many people use block heaters in Florida ..yet they too experience the unavoidable startup/warm up wear and side effects that insult oil ...only to a lesser degree. That is, you're only compensating for extreme environmental variables. That paintbrush can't be broadly applied ..or won't be by the mass motoring public

That's why high % of your wear is unavoidable. You can alter the excessive wear ..and that's about it. It's in the genes (visions of Tyrel as Roy confronted him in Bladerunner, "We've built you as good as we could"). The wear is inherent to reciporcating combustion driven engines. It's what turns all cylinders oval eventually in all piston engines.

 

[JAG]

Yep, agreed. Here's some personal experience of mine with my oil pan heater. I generally use it when it's below 35F or so. It definately makes the startup sound like it's not nearly as cold out. Actually, the first split second does sound bad like it normally would at those temps, and suddenly the sounds become nice and smooth like it does when I start it in warmer weather. And I've touched the oil pan as it idles after the start up and the pan never does drop down to ambient temps (it's scolding hot before I start it). That's good news - oil remains less thick during entire warm up phase than it would have been otherwise and some of the oil's heat is tranfered to the engine itself (evidenced by the cooling of the pan in the first minute or so).

There were some block heater tests done in Scandinavia and they measured emissions with and without the block heater. Test results are somewhere on the internet. The block heater greatly decreased the emissions as we would expect (it simulates starting at a warmer temp as you said). This indicates the combustion is much more complete and closer to appropriate A/F ratio when the temperature inside the cylinders is increased.

 

[LarryL]

So, we have our engine figured out. A pan heater, synthetic oil, a bypass filter, a cleanable stainless steel full flow filter, careful driving and maintenance, park in the garage, Auto-RX every couple of years, LC to hold the TBN and negate the effects of moisture, and LC to protect the fuel system. And if you do all that, please post you car when you sell it.

 

[Gary Allan]

So, we have our engine figured out. A pan heater, synthetic oil, a bypass filter, a cleanable stainless steel full flow filter, careful driving and maintenance, park in the garage, Auto-RX every couple of years, LC to hold the TBN and negate the effects of moisture, and LC to protect the fuel system. And if you do all that, please post you car when you sell it.


Zactly!! It will die in much better health than other cars without such care (vision of my doctor being so pleased when I quit smoking. He said that it pleased him that I'd die in much better condition

)

 

[SKUNKY]

"I don't doubt that that statement is true. The degree to which it is true should be the question. So what if most of the wear to an engine does occur at start up? How much wear are we really talking about and what could be done about it, realistically? I doubt it is an amount that should keep someone awake at night, since just about any well maintained engine is good for 100k miles or more. Even 200k miles or 300k miles is fairly common enough, and all of those engines had start-ups for their entire lives and some degree of start-up wear. I think I'd rather worry about something more productive myself."
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