Really? Brittle rings and cold oil???

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There is a forum member over on the Pilot forum who just responded to an owner who lost his engine with 118000 miles on it. This member has posted this statement which I find to be, well for lack of a better word, hogwash!

"This seems like oil starvation. It will take a full tear-down to identify the source of the metal fragments, but I would bet on rings. Quick changers don't give the super hot engine internals a chance to cool down to ambient (room) temperature before refilling with cold oil. That causes thermal shock, which some brittle metals (rings) don't cope well with.
...
That's why I do my own oil changes, and always let the engine cool off at least one hour while letting every last drop of old oil drip 💧 out into the pan, then pre-fill the new filter also to prevent oil starvation on the first start."

First, engine internals are not going to cool down to ambient temperature within one hour. Adding oil is not going to cause thermal shock on "brittle rings", correct.

Here is a link if you want to read what happened to the owners engine and some of the discussion so far.
 
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Yeah you're correct it's a load of it, starting a modern power dense engine below 20 degrees would produce more of a delta in temperature over a shorter period then using room temperature oil in an engine that's been run under normal conditions and not given time to cool down. Now with that said if you took an S2000 or 370z and wailed it around a track for an hour or two I could see the wisdom in letting everything cool down for several hours before changing the oil, but that's from a plastic oil pans and filter housings and valve covers and or their gaskets perspective.
 
Oil has a fairly low specific heat, so I doubt you could thermally shock an engine bad enough to cause damage that way. "Shock" cooling is (was?) a pretty common test done by car manufacturers anyway, by suddenly & severely dropping the coolant temp on a loaded engine in a test cell.
 
Sounds like neglect, or a bad engine. Even Honda turns out an engine or two that fail.
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Originally Posted by cjolson140
Oil has a fairly low specific heat, so I doubt you could thermally shock an engine bad enough to cause damage that way.


To add, the oil that comes into contact with the rings is a very small volume (a thin film), so it has hardly any thermal mass to cause parts to be "thermally shocked".

Whoever came up with this wild "shock" theory doesn't understand heat transfer.
 
Agreed; that is complete and total hogwash.

If that were true, every single oil-change quick-lube and dealership would have to let vehicles cool down for at least an hour, or risk huge volumes of lawsuits from the unavoidable doom of shattered pistons and such. And every single owner's manual is at the cusp of legal malfeasance because not one I've ever read states to let and engine cool down or risk engine death.

Yeah - right ...
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Ive always found a hot or warm engine, reheats new oil as its put in. Its actually much better than putting cold oil in a cold engine on start up
 
Anything you read on an internet forum of any kind, you need to take with a grain of salt.
 
To change the oil … I start the engine and then pull up on the ramps … change when warm, not hot.
And to think all these years I thought it was because I did not like pain …
What a feeling to know it was for a greater cause ! ...œ
 
Originally Posted by tom slick
I'm curious how pouring cold oil into the engine gets in hot rings. It must jump up from the sump!

Kind of what I was thinking .
 
Originally Posted by ls973800
That's why I do my own oil changes, and always let the engine cool off at least one hour while letting every last drop of old oil drip 💧 out into the pan


I just put my bottles of oil in the microwave to heat it up first before pouring into the engine. No thermal shock then.
 
Originally Posted by atikovi
I just put my bottles of oil in the microwave to heat it up first before pouring into the engine. No thermal shock then.


But then the oil is IRRADIATED! /joke
 
Originally Posted by atikovi
Originally Posted by ls973800
That's why I do my own oil changes, and always let the engine cool off at least one hour while letting every last drop of old oil drip 💧 out into the pan

I just put my bottles of oil in the microwave to heat it up first before pouring into the engine. No thermal shock then.

I hope no one even considers doing this. It is stupid and irresponsible to even say something like that.
 
Originally Posted by Rand
Originally Posted by atikovi
I just put my bottles of oil in the microwave to heat it up first before pouring into the engine. No thermal shock then.


But then the oil is IRRADIATED! /joke


Gives rise to the question of tin foil hats forming a Faraday cage
 
I'm usually a polite person, but these are the times such as this where I wish I could point and laugh in the guy's face.
 
Originally Posted by PimTac
Originally Posted by atikovi
I just put my bottles of oil in the microwave to heat it up first before pouring into the engine. No thermal shock then.

I hope no one even considers doing this. It is stupid and irresponsible to even say something like that.

I've actually set the bottles on the heat register outlet in the house to warm them up in winter, so I can get more oil to drain out of them. No wonder I've never blown up any engines at an oil change yet!!
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