Why is oil temp so important?
13 February 2007, 08:15 PM
#1
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Why is oil temp so important?
Now this might be a muppet question....... but can someone explain.....
I understand that the engine needs to be at the correct temp before opening the taps, but why must I wait for the oil temp?
If oil pressure is good and engine temp good then is there any need in waiting for the oil temp to reach optimal temp?
The reason I ask is that I wait until engine temp is good (on standard gauge) then wait another 5 mins for oil temp..... but is waiting for oil temp really necessary? I find my self driving like Miss Blooming Daisy for 3/4 of my journeys because of this!!!
Plums.
I understand that the engine needs to be at the correct temp before opening the taps, but why must I wait for the oil temp?
If oil pressure is good and engine temp good then is there any need in waiting for the oil temp to reach optimal temp?
The reason I ask is that I wait until engine temp is good (on standard gauge) then wait another 5 mins for oil temp..... but is waiting for oil temp really necessary? I find my self driving like Miss Blooming Daisy for 3/4 of my journeys because of this!!!
Plums.
14 February 2007, 04:36 PM
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Not at all!
Good oil pressure doesnt mean good oil flow. Warmer oil will flow more and hence more will get to where it needs to be rather than just opening the oil pressure relief valve and going back to sump.
Good oil pressure doesnt mean good oil flow. Warmer oil will flow more and hence more will get to where it needs to be rather than just opening the oil pressure relief valve and going back to sump.
14 February 2007, 04:43 PM
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What you call your 'engine' temperature is your water temperature. However, your crank journals, bearings, pistons, rings, cylinders, cam journals etc. obviously see the oil. Its these components that are in contact and 'rubbing' so they need a protective layer of oil.
Pressure is not the be and end all, when your oil is colder you will have more pressure but not necessarily better protection.
I'm no chemist, but your oil is designed to work within a given temp range. Above this temp it all becomes a bit too thin and the oil molecules can slide over each other easily i.e metal to metal contact is far more frequent/likely.
Below this temp, its all a bit thick and stodgy, the molecules are like glue and the oil just does not flow. remember flow and pressure are not the same.
Someone with a better knowledge of lubricants will give a better explanation.
Pressure is not the be and end all, when your oil is colder you will have more pressure but not necessarily better protection.
I'm no chemist, but your oil is designed to work within a given temp range. Above this temp it all becomes a bit too thin and the oil molecules can slide over each other easily i.e metal to metal contact is far more frequent/likely.
Below this temp, its all a bit thick and stodgy, the molecules are like glue and the oil just does not flow. remember flow and pressure are not the same.
Someone with a better knowledge of lubricants will give a better explanation.
14 February 2007, 08:04 PM
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Nice one P1,
That is exactly what I thought....
I'm guessing the theory really stands for the thicker oils 10W and more?
I imagine lower viscocity oils flow easier and sooner?
I know 0W oils are frowned upon, I'm currently running a 5W during the winter months.
Anyone know how much longer it takes for the oil to reach optimal temp after the water temp is has?
Cheers,
Plums.
That is exactly what I thought....
I'm guessing the theory really stands for the thicker oils 10W and more?
I imagine lower viscocity oils flow easier and sooner?
I know 0W oils are frowned upon, I'm currently running a 5W during the winter months.
Anyone know how much longer it takes for the oil to reach optimal temp after the water temp is has?
Cheers,
Plums.
14 February 2007, 08:27 PM
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I think when my water temp reaches the middle of the gauge my oil temp just begins to reach 40degreesC within two minutes after that its at about 60c but with out setting off it takes about 5 mins to get to 80c and isnt likely to go higher than this with out increasing engine speed. Once it reaches 60c I usually set off and drive under 2-3krpm untill it reaches 85c.
Its not going to heat up quickly without driving and to be fair its not likely to do much damage running off-boost when its at 60c, after all it is only a 2.0litre when running off boost.
Gaz
Its not going to heat up quickly without driving and to be fair its not likely to do much damage running off-boost when its at 60c, after all it is only a 2.0litre when running off boost.
Gaz
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