Engine failure due to low oil temps?

[Gary Allan]

Although I can see aircraft applications being critical and I believe that we are talking about "oil cooled" applications here (and I'm actually surprised that "coolant" temp is so broad on these IC engines), and that diesels are another animal, I can't for the life of me believe that a passenger car engine manufacturer factors oil temp to such a narrow range. That is, imperical data, although not comprehensive, suggests that typical passenger car use, in engines that actually monitor oil temp, vary widely from engine to engine and from one mode of operation to another(highway, city traffic, etc.). There, to my knowledge, is no metering, or regulation of oil flow/temperature in any of the engines that tyically monitor oil temp (OEM cooler equipped being the exception)....and NONE in vast majority of domestic iron that I know of. That is, no cooler, thermostat, etc. Hence, I have to conclude that this is a non-factor of any consequence in the design of the average engine. The only thing that I can think of that would possibly (to me- but I'm

)factor in is that the chosen viscosity (especially in most of the Euro machinery) may be very critical at high speed operation ..and running the oil too cool actually simulates a higher viscosity than the engine can tolerate in that operational mode. Naturally I'd really love to get the real "fat" on this from the actual specific engine manufacturers.

 

[Alan]

Engines last longer nowadays due to higher oil temps.Back in the old days engines ran cooler and got more deposits because of this,resulting in shorter engine life.

Usually engines run more efficiently at a peak optimal temperature the is usually regulated.Audi would know this better than anyone.All you need is an oil up to the job.

 

[Mickey_M]

quote:

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Originally posted by 427Z06:

The crankcase has a lot of air circulation with that crank whipping around. New air is constantly being introduced through the PVC system. Blowby is composed of hot gases.

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All in a closed space. Like the shower when you shut the door. One of the gases in blowby is water vapor.

quote:

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What was the point you were trying to make?

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That there is no comparison between a crankcase and a glass of water.

 

[TC]

"Girlfriend ran a Geo Metro without a thermost in winter in NYC...the temp gauge needle would never move off rest position. (Hmmm, for that matter, neither would the needle move off rest position in the hottest Summer!)"

HA!!! An engine in which you'll get burned if you press your hand against it...a FREEZER burn! Don't stick your tongue against that engine...it'll stick!

 

[427Z06]

quote:

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Originally posted by Mickey_M:

quote:

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Originally posted by 427Z06:

The crankcase has a lot of air circulation with that crank whipping around. New air is constantly being introduced through the PVC system. Blowby is composed of hot gases.

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All in a closed space. Like the shower when you shut the door. One of the gases in blowby is water vapor.

quote:

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What was the point you were trying to make?

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That there is no comparison between a crankcase and a glass of water.

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I'm giving up on this one. I think both our analogies are bad here.

I'll just add this. I changed a lot of oil in the 60's and 70's when I lived in upstate NY on engines that had 160F thermostats and were driven mainly on short trips and never did I see water contamination that was visually discernible in any vehicle that was properly maintained.

I suspect the original poster has other issues.

[ October 09, 2004, 09:57 PM: Message edited by: 427Z06 ]

 

[Eddie]

Years ago Porsche stated that engine oil oil should be maintained at a minimum temp of 180 degrees F. for maximum lubracating properties and oil life. I think the the maximum was suggested to be less than 220 degrees F. So Porsche recomendes an oil temp of between 180-220 degrees for max oil and engine life. ed

 

[Gary Allan]

quote:

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Engines last longer nowadays due to higher oil temps.Back in the old days engines ran cooler and got more deposits because of this,resulting in shorter engine life.

Usually engines run more efficiently at a peak optimal temperature the is usually regulated.Audi would know this better than anyone.All you need is an oil up to the job.

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I disagree somewhat. Engines last longer today because of infinitly superior fuel management and more efficient fuel utilization. This mandated higher engine temperatures ..and the subsequent higher oil temperatures. This is, higher oil temps may have been higher or lower in an older car due to various factors ..but in a newer car I would say that the impact of higher coolant temps definitely effect mean oil temp on the vast majority of the cars on the road today.

The ONLY truth to the "glass of water" is that you DON'T have to get anywhere near BOILING (as was asserted for those who actually care to track it back) to vaporize water. It's that "one dimensionally" simple.

The rate of suspension of moisture is higher (that is, faster) with increased temperature. Keep in mind that the moisture introduced by combustion is ALREADY IN VAPOR FORM. It is only when this moisture is allowed to repeatedly accumulate in a warm up/shutdown situation that won't allow it to go back into suspension (vaporize) and be evaculated that it causes a problem. This WON'T happen at sustained oil temps of 180 ..150...or even 125 F (probably). The stuff coming into the crankcase will still leave. The reisdual moisture that condenses will remain condense ONLY if the oil temp, however low, doesn't remain heated LONG enough to facilitate the moisture's complete suspension. This isn't rocket science in concept. Moisture condenses when the engine is cold ..moisture condenses when the engine cools. Moisture doesn't condense when the engine is warm.


I've never EVER heard of a lubrication related failure, in a passenger car engine anyway, due to too cool a lubricant temp (in terms of "warmed up" too cool). I'd like to see the damaged bearings that were maintained @ 180 F fail before bearings maintained @ 220 F (broaden span until you feel justified). That is, if the "normal" temp range was 160-190 ...do any of you think that you would actually see any additional wear? Wear that would not be apparent with an out of spec oil (read-different viscosity will be realized at cooler temp)???

I would like to be shown this from an authoritative source.

 

[Ken2]

Oil does need to be normally warm, and that has little relationship with the coolant thermostat.

Perma-Cool sells a thermostatic bypass valve for their oil coolers that is set at 180°F. That means that the oil doesn't begin flowing through the air-cooled cooler until the oil temperature reaches 180°F and the bypass valve doesn't get fully open and send all the oil through the cooler until the temperature is somewhere above that.

I, too, am skeptical about, "you could see the oil separating from the other contaminants in the bucket." Fuel will not separate from oil. Water emulsifies in detergent oil. If there was much water in the oil, the oil would be milky.


Ken