Checking motor oil: Hot or Cold?
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The Spanish Stallion
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Checking motor oil: Hot or Cold?
Okay did a couple of quick searches and couldn't find anything really. Anyhow, when checking the motor oil level, is it best to check it when the engine has been sitting cold or is it best to check it when it's already hot? I ask because everybody has a different answer, but I want something more conclusive. Thank you in advance.
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As far as I know ideally it should be checked it with the engine cold so all the oil can be drained into the pan. At least thats what is recommended for piston engines. I don't think it really matters though...lol. Probably a 0.1 quart of a difference if that.
For draining oil the engine should be warm.
For draining oil the engine should be warm.
#7
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Too bad there isn't a FAQ on this forum with a link to a free scanned online service manual so you could check and see if 3 out of 4 respondents to this thread gave you the wrong answer.
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#10
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Actually i tested today. I checked my oil level before i went for a drive (first start up of the day) and went for about 30 mins ride. Parked it and waited for 5 mins and check my oil level again.
It seems to be the same, but i am not running omp (just premix). Engine is an 88 AE.
It seems to be the same, but i am not running omp (just premix). Engine is an 88 AE.
#11
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Oil expands when hot and contracts when cold. The difference between a hot and cold reading depends on the temperature difference and the dimensions of the oil pan. You will not see any significant difference on an RX-7 if you live in a warm environment. Those who live in a cold environment will probably see a 1/2 qt difference. The main reason for checking the oil when warm is to avoid over-filling the engine. You can check it cold to make sure it is at or above the minimum level, but don't top it off to Full when cold.
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Makes sense, thanks for the thorough answers. Eventhough I neglected to check the FSM (I frankly didnt think the answer would be there), I appreciate the insight from everyone, specially Evil Aviator.
#15
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True, but an insignificant amount.
According to this chart, unused motor oil expands .00039% for every degree Farenheit, so assuming an ambient temp of 75° and a running temp of 180°, the volume of oil has expanded .04095%.
Our cars take roughly 5 quarts of oil, which is 160 fluid ounces, so it would expand by @6.5 ozs.
There must be another reason for Mazda's suggested method because expansion of the oil volume is trivial.
According to this chart, unused motor oil expands .00039% for every degree Farenheit, so assuming an ambient temp of 75° and a running temp of 180°, the volume of oil has expanded .04095%.
Our cars take roughly 5 quarts of oil, which is 160 fluid ounces, so it would expand by @6.5 ozs.
There must be another reason for Mazda's suggested method because expansion of the oil volume is trivial.
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True, but an insignificant amount.
According to this chart, unused motor oil expands .00039% for every degree Farenheit, so assuming an ambient temp of 75° and a running temp of 180°, the volume of oil has expanded .04095%.
Our cars take roughly 5 quarts of oil, which is 160 fluid ounces, so it would expand by @6.5 ozs.
There must be another reason for Mazda's suggested method because expansion of the oil volume is trivial.
According to this chart, unused motor oil expands .00039% for every degree Farenheit, so assuming an ambient temp of 75° and a running temp of 180°, the volume of oil has expanded .04095%.
Our cars take roughly 5 quarts of oil, which is 160 fluid ounces, so it would expand by @6.5 ozs.
There must be another reason for Mazda's suggested method because expansion of the oil volume is trivial.
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Always check your oil level with the engine fully warmed up, and the engine off for at least a few minutes.
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