oil level

[phatcat]

I noticed that my oil pressure was a bit low at idle, so I set about checking the oil level.

 

The 1.6K engine has a big label on it saying check oil level when hot - fair enough.

 

However, out of interest, I took a reading when cold and a reading when hot.

 

When cold, the oil level was slightly above max, and when hot it was slightly below min.

 

This seems odd, as I'd expect hot oil to expand and give a higher oil level reading, but apparently not.

 

1. I assume this is normal?

2. Why?

 

 

[phatcat]

Anyone...? Bueller... Bueller...?

 

 

[davidvoas73]

My theory would be that when cold the oil has had a chance to return to the sump, when hot the oil is still coating all those precious bits of metal....

[Slipper man]

That's exactly right. When cold, all the oil drains down to the bottom of the engine. When hot, the oil pump sucks oil from the sump, and pumps it to the moving parts, such as the cans and crankshaft.

 

The actual oil level doesn't matter very much unless you are using it on a circuit. So long as there is enough to ensure the oil pump is never sucking air, you will be ok. The only problem with over filling will be the potential to have oil blowing out of the breathers, which is not good, but not a disaster (for the engine).

 

My advice would be to set the oil level in the middle of the dipstick guides when warm.

[Tony C]

I'd echo pretty much all the above, except to disagree with the "The actual level doesn't matter very much except on track." It's your engine of course! The recommended method is to fill to the full mark on the dipstick with the engine at full operating temperature with the engine RUNNING, rather than the mid point.

 

From cold you'd need to let it idle for a good 15 - 20 minutes to get the oil up to temperature.

 

I've now got a dry sump, but once I'd got the level correct as above, I'd check the oil level with the engine still running after a blat. Make sure you stop the engine before adding though. With the oil at the mid level on the stick it doesn't take very much to bring it to the full mark 😬

 

BRG Brooklands SV 😬 It seems that perfection is achieved not when there is nothing more to add, but when there is nothing more to take away. (Antoine de Saint-Exupery)

 

Edited by - Tony C on 12 Mar 2005 13:37:32