BMW engine oil capacity - why?

[imbalance]

Does anyone here have "insider" knowledge as to why BMW usually ask for 6.5L of engine oil in their 3.0L engines? I think even the B25 (2.5L) motors take 6.5L of engine oil. Have BMW done this with safety or a buffer in mind? In case there is oil consumption or leak? Reason I ask is because these eDipsticks are rubbish. It won't show me I am low on oil until I am like 1.5L low. I have tested this with an old and new sensor. For example engine capacity is 6.5L but if I only fill 5.0-5.5L, it shows full. I have some mystery oil leak which I cannot locate and the oil sensor says oil is full so I am worried about running too low because I have no real dipstick to look at. The old 2jJZGTE engine was a twin turbo 3.0L engine too and it had an oil capacity of like 5.0L, the VR30DTT engine also only takes about 5.5L of oil. Is this just something BMW (or German manufacturers in general) have put in place for safety so that I can afford to run it low on oil (until I find and fix this leak) and still be fine because more is refilled than required?

Edited by imbalance on Sunday 7th September 17:31

[mmm-five]

It's not a consumer safety feature - it's just the amount BMW engineers have decided/calculated that they need to keep everything lubricated.

[imbalance]

mmm-five said:

It's not a consumer safety feature - it's just the amount BMW engineers have decided/calculated that they need to keep everything lubricated.

So then why would it not tell me engine is low on oil until the level falls more than 1.5L below max?

[g3org3y]

mmm-five said:

It's not a consumer safety feature - it's just the amount BMW engineers have decided/calculated that they need to keep everything lubricated.

Yes, I think my previous M50 2.5, M52 2.8 and M54 3.0 were all the same.

imbalance said:

So then why would it not tell me engine is low on oil until the level falls more than 1.5L below max?

I suppose 6.5 litres is the max.

Min to Max is 1l so I'd expect the Min (and the trigger to add 1l) is 5.5 litres?

When you say you have a mystery oil leak, is it just high oil consumption? How much is it using per 1000 miles? Have you considered the PCV. Clogged PCV = high oil consumption.

[imbalance]

g3org3y said:

mmm-five said:

It's not a consumer safety feature - it's just the amount BMW engineers have decided/calculated that they need to keep everything lubricated.

Yes, I think my previous M50 2.5, M52 2.8 and M54 3.0 were all the same.

imbalance said:

So then why would it not tell me engine is low on oil until the level falls more than 1.5L below max?

I suppose 6.5 litres is the max.

Min to Max is 1l so I'd expect the Min (and the trigger to add 1l) is 5.5 litres?

When you say you have a mystery oil leak, is it just high oil consumption? How much is it using per 1000 miles? Have you considered the PCV. Clogged PCV = high oil consumption.

Yes 5.5L should trigger an add 1L message but for me it does not. Google shows I am not the only one, for example: https://www.e90post.com/forums/showthread.php?t=42...

It could be a minor consumption but there is definitely a leak. I can see the oil drops but it makes no sense where it is coming from. I have checked the places it could leak out from but they are dry. It is hard to get a good look at everything because of how crowded the engine bay is but I clean the area where I see the oil drops and check for leaks and sometimes it does not appear, sometimes it appears somewhere else and sometimes it appears in the same place again. I have taken care of most gaskets too. It loses about 150-200 mL per 1000 miles but it is not always consistent. I have measured this figure by measuring what drains out during oil change. I have not really thought about a clogged PCV yet and will look into it. However there is no smoke from the exhaust.

Edited by imbalance on Sunday 7th September 19:26

[Pica-Pica]

Some do still have a manual dipstick, the 335 diesel does.

[Mr Tidy]

I'm on my third 3 litre N52 and they all take 6.5 litres, and have all leaked a bit at higher mileages!

As a result I made a point of checking the oil level every time I used the cars so I could top them up before they got to minimum level. It also meant I knew when the engine was up to temperature because the level function only works after that, and my 330i doesn't have a temperature gauge.

Strangely my Z4M with the 3.2 litre S54 engine only takes 5.5 litres, but hardly uses any and has a proper dip-stick too.