I've always been a little curious. I know it's a bad idea to pour water into an overheating engine that has lost coolant because it will cool parts of it faster than others, and in some cases you can crack the block. So let's say I'm changing the oil, the new oil has been in my unheated garage in freezing temperatures, and the engine is still hot. For that matter, let's say I went to (gasp) a quickie lube place. Wouldn't putting cold oil into a hot block potentially cause similar problems? I guess I can say I've not heard of it happening, but I have been leery of pouring cold oil into an engine that's still hot.
Cold oil, hot engine... Bad?
- Thread starter Dave Sherman
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No problem. The engine is normally warm, not hot as in overheated. Also, the oil doesn't carry as much heat away as water, so even if the temperatures were the same, the oil has less cooling effect.
I would think oil that is really COLD (as opposed to room temp) wouldn't pour fast enough to do damage.
Also the volumes of oil compared to the volumes of coolant are smaller. I.E. adding a quart or 4 quarts of oil vs adding several gallons of coolant.
The oil is going to drain through the engine and settle in the oil pan, while coolant will remain in the block.
So I don't think adding a quart or four to a hot engine is a dangerous practice. (As long as we are not talking about an overheated engine, that is...)
Also the volumes of oil compared to the volumes of coolant are smaller. I.E. adding a quart or 4 quarts of oil vs adding several gallons of coolant.
The oil is going to drain through the engine and settle in the oil pan, while coolant will remain in the block.
So I don't think adding a quart or four to a hot engine is a dangerous practice. (As long as we are not talking about an overheated engine, that is...)
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