How to measure the oil level on an E39 M5

According to the label on the dipstick, I should run the engine for 15 seconds, wait 1 minute then dip the oil.

Fair enough but:

1. When cold (started+left 1min), I get a reading 25% up from low

2. When hot (started+left 1min), I get a reading 25% down from full.

3. When left overnight and just checked without starting the engine, I get exactly full.

Now I could add 750cc of oil to make test 1 read "full" but then the other two tests would be overfilled. 

What's the experience/advice?

Andy

I've used option number 1 to test the oil level, but like you get variable readings using the other options.

So mostly I wait for the bong and the display to tell me to check oil level.....

Thanks for the replies, I guess I should wait for the gong then.  Although it's a bit of a leap of faith...  Plus all my journeys are long!

Do you guys still have the little plastic printed label attached to the finger hole in the top of the dipstick?  That's where I read the "Idle engine for 15 seconds, leave for 1 minute" advice.  I totally agree that this leaves oil in other parts of the engine than the sump, but I guess the dipstick must be calibrated for that method.

Also, like you say when it's hot more oil will drain back to the sump during the minute so the reading will be higher.  The label doesn't say hot or cold, so the "1 minute" bit seems rather unscientific.

I guess the good news is that after a couple of thousand miles the levels don't seem to be going down much.

Andy

No tag on my dipstick !!!

The owners manual (page 143) states :

1 Position the car on a flat level surface

2 If the engine is at its regular operating temperature, allow it to idle for 15 seconds, then switch off

3 Wait about 1 minute, then take out the dipstick and wipe it with a non-fluffy cloth or similar

4 Carefully push the dipstick fully it to its tube, then pull it out again

5 The oil level must be between the two mark on the dipstick

It also says that the quantity of oil between the two marks is approx 1 litre. So I work on the premise that when the bong goes it must be near the lower mark and then I chuck in a bottle of TWS. Like you most of my journeys are long, in excess of 90 miles each way. So I always have a spare bottle in the boot.

The handbook also says :

Do not add more oil until the level has dropped almost as far as the lower distick mark.

So again the bong principle is a good as any other I'd guess as I normally get about 3k miles between bongs.

On my M5 the warning light comes on first(since last top up) after a long sprited drive. The engine will be espically warn then and the oil reading will be at it's lowest. Next time I use the car from cold and drive normally the warning light does not come on at all.

Depending on your car it might be different. But if I check my dipstick at the first warning light(since last top up) after it's cooled down it would be only halfway down the dipstick. So if I put a litre of oil in I would have 0.5l too much in it.

Always check the level before putting in oil. Don't assume the level.

I do burn about 1 litre every 500miles. Loads of city driving and I have a very heavy right foot. Also I do between 9-11mpg.

I have heard that waiting for the oil light to come on before topping up is not very good for the engine, especially on a car like the M5 where it is highly tuned.