Preffered engine oil check.

[tonysmb]

Totally agree on the checking period. Once up to temp. Then check 5/10 mins after shutdown. Is a pain it has to be said

I'm not sure that these interpretations are correct, although I have seen it quoted on this forum several times.

I currently have 3 MBs (and have had several others previously) and none of them state this in the handbook. What they do state, however, is IF (my capitals) engine is at normal running temperature, leave for 5 minutes before checking the oil level. IF engine has been started briefly but not reached running temperature, leave for 30 minutes before checking oil level.

What isn't stated but is a reasonable assumption from the above is that the time delay is to allow the oil to drain back to the sump. I have not seen any reference to 'oil level must be checked when hot'. I acknowledge that oil will expand slightly when hot. I do have other cars where, for example, the handbook specifically states that the transmission level must ONLY be checked when at normal operating temperature.

Dipstick for me everytime.

 

[Bobby Dazzler]

I'm not sure that these interpretations are correct, although I have seen it quoted on this forum several times.

I currently have 3 MBs (and have had several others previously) and none of them state this in the handbook. What they do state, however, is IF (my capitals) engine is at normal running temperature, leave for 5 minutes before checking the oil level. IF engine has been started briefly but not reached running temperature, leave for 30 minutes before checking oil level.

What isn't stated but is a reasonable assumption from the above is that the time delay is to allow the oil to drain back to the sump. I have not seen any reference to 'oil level must be checked when hot'. I acknowledge that oil will expand slightly when hot. I do have other cars where, for example, the handbook specifically states that the transmission level must ONLY be checked when at normal operating temperature.

Dipstick for me everytime.

There are two reasons for checking when the engine is at operating temperature:

1. Oil expands when hot and so the oil will be higher on the dipstick with hot oil. Checking the oil when hot reduces the risk of overfilling.

2a. It enables consistency, because the effect of ambient temperatures and oil temperatures are much reduced.

2b. It enables consistency when measuring at the roadside, ie unscheduled checks (when waiting for oil to cool is impractical).

 

[E55BOF]

...It enables consistency, because the effect of ambient temperatures and oil temperatures are much reduced...

So does checking it stone cold...

 

[Bobby Dazzler]

So does checking it stone cold...

Consistent when stone cold in winter or summer? At night or in the day? In Scandinavia or the Mediterranean?

How does it deal with oil temperature when at home on the drive after a week of standing still, or at Motorway services after 200 miles?

 

[Peter103]

Popcorn anyone?

 

[Bobby Dazzler]

Stone cold will be OK, just stay away from the max mark.

 

[Peter103]

Interesting, and enlightening, I usually check mine after shopping with S W M B O, after carting in all bags with car in garage and hot 10mins later, so far I've never had to top it up, cars now on 65000mls plus a few more.

 

[350cls]

In my experiences when checking the level with a dipstick on a (cold) engine is the level on the stick is always a different reading, every time the stick is reinserted and pulled. The first pull of the stick seems to give the most accurate (cold) reading.

With the manual check I find on the 6.2 to get the engine up to temp. When shut down check after 5/10 minutes. Gives me the most accurate reading time after time.

Works for me, no trouble at all in 16 months of ownership.

The digital option is a lot less fafing about. Not as messy also.

on the s211 e320 can read the exact amount of oil also.

i think like been stated above, there is good argument for both methods.

 

[geoffus]

There are two reasons for checking when the engine is at operating temperature:

1. Oil expands when hot and so the oil will be higher on the dipstick with hot oil. Checking the oil when hot reduces the risk of overfilling.

2a. It enables consistency, because the effect of ambient temperatures and oil temperatures are much reduced.

2b. It enables consistency when measuring at the roadside, ie unscheduled checks (when waiting for oil to cool is impractical).

Found this on the internet, unless i'm wrong, oil does not expand by that much.



Volumetric expansion coefficients of some common liquids

(1/K, 1/oC)	(1/oF)
Liquid	Volumetric Coefficient of Expansion
Oil (unused engine oil)	0.00070	0.00039

 

[Bobby Dazzler]

Found this on the internet, unless i'm wrong, oil does not expand by that much.



Volumetric expansion coefficients of some common liquids

(1/K, 1/oC)	(1/oF)
Liquid	Volumetric Coefficient of Expansion
Oil (unused engine oil)	0.00070	0.00039

How much oil is in your engine? Shall we say 8 litres?

What’s the average ambient temperature and therefore temperature of oil in a “stone cold“ engine? Shall we say 7 deg C?

What’s the average operating temperature of oil? Shall we say 100 deg C?

Seems reasonable to me. That’s 0.5 litres right there.

Many drivers fill to the “max” mark on a cold engine, that 0.5 litres of oil could push beyond the maximum on a trip to the supermarket.

Filling to the mid point between kin and max should mean that you can expand by up to 1 litre (not likely!) without exceeding max!

 

[Bobby Dazzler]

How much oil is in your engine? Shall we say 8 litres?

What’s the average ambient temperature and therefore temperature of oil in a “stone cold“ engine? Shall we say 7 deg C?

What’s the average operating temperature of oil? Shall we say 100 deg C?

Seems reasonable to me. That’s 0.5 litres right there.

Many drivers fill to the “max” mark on a cold engine, that 0.5 litres of oil could push beyond the maximum on a trip to the supermarket.

Filling to the mid point between kin and max should mean that you can expand by up to 1 litre (not likely!) without exceeding max!

PS @geoffus for every £8 tied up in equity in your property(s) can you give me 50p, and then a further 50p for every £8 of income please? It’s not that much.

 

[Justintyme]

Bottom line (for me anyway ) in the OM651 engine, official oil capacity is 6.5 litres, so after draining it, I fill 6 litres then drive it, check for leak's etc, then leave it overnight. Check again first thing next morning, and top it up as needed. The reason that I only fill with 6 Litres is to allow for any amount that did not drain out during the change. By leaving it overnight, I will be able to see the correct level on the dipstick when I dip it. and I can change it accordingly. So it will have the correct amount in it. IE: 6.5 litres. You have to bear in mind that when refilling it, the oil will not be hot, but still measure 6.5 litres by volume, and this is the design amount to have in the engine.

 

[geoffus]

PS @geoffus for every £8 tied up in equity in your property(s) can you give me 50p, and then a further 50p for every £8 of income please? It’s not that much.

Fair enough, please send me your bank details and mother’s maiden name.

 

[E55BOF]

It seems obvious to me that the five minute/thirty minute recommendation is to allow all the oil to be down in the sump when the level is checked, and has nothing whatsoever to do with its temperature when checked. Does anybody believe that Mercedes's engine designers are so incompetent that they do not specify minimum and maximum oil levels that incorporate tolerances for both temperature and some accidental overfilling anyway?

Unless an engine is grossly overfilled with oil, expansion of the oil as it heats up is irrelevant. As soon as the engine turns and the oil starts circulating, the oil level in the sump drops dramatically. Try watching the oil level in the sight glass on a motorcycle engine side case when it's started to see what I mean.

I do exactly what Justintyme (post 32) does. I've been doing it for fifty years, in the UK, Hong Kong and Berlin, and never had a problem. I'm inclined to think it's a satisfactory procedure, but I don't suggest it's the only one.

 

[geoffus]

They will be telling us to check our tyre pressures when warm next !!

 

[zipdip]

Well I used to check with the dipstick,but now with my car using no oil between services I just look at the dash message when I start up with says oil level correct.

 

[daveenty]

Without getting into arguments regarding the correct time to check, going back to the method used I much prefer a dipstick though it does seem to be a vanishing option nowadays.

The reason for this is not just to check the amount but it's a lot easier to see the quality which can tell an awful amount about the health of the motor. Clean, fresh looking/smelling oil = good. Dirty, black and sooty = less so.

That was how we were brought up to check the oil on stuff, the same applies to transmissions, at least to me...

 

[geoffus]

Without getting into arguments regarding the correct time to check, going back to the method used I much prefer a dipstick though it does seem to be a vanishing option nowadays.

The reason for this is not just to check the amount but it's a lot easier to see the quality which can tell an awful amount about the health of the motor. Clean, fresh looking/smelling oil = good. Dirty, black and sooty = less so.

That was how we were brought up to check the oil on stuff, the same applies to transmissions, at least to me...

That’s ok with petrol motor, but diesel will look thin and dirty in a very short time unless you manage to drain the oil cooler or flush it first. I’m old school and always check with a dipstick in the morning on a cold motor on my level drive.

 

[daveenty]

That’s ok with petrol motor, but diesel will look thin and dirty in a very short time unless you manage to drain the oil cooler or flush it first. I’m old school and always check with a dipstick in the morning on a cold motor on my level drive.

In nearly 50 years of driving I've never owned a diesel, so no problem there.

 

[gianton]

That’s ok with petrol motor, but diesel will look thin and dirty in a very short time unless you manage to drain the oil cooler or flush it first. I’m old school and always check with a dipstick in the morning on a cold motor on my level drive.

+1 same here