Checking oil, back to basics? - The Unofficial BMW M5 Messageboard (m5board.com)

kwalls · 24th April 2003, 13:03

Since there have been numerous posts on subject of oil consumption with the M5, I have been more diligent than previously to check my oil. To date, I had seen very little consumption during the break-in period and was anticipating similar results now that I had the German recommended 10W-60 oil installed.
Monday on the way to work I stopped at the local gas station before getting on the autobahn for a fillup. After topping off the tank I decided to check the oil again (last time I had checked it was Friday morning before my attempts to find top speed). Imagine my surprise when the dipstick showed I was down approximately ½ a liter. Couldn’t believe it, so I checked again. Maybe I had screwed up the procedure. So, one more time with precision. Yep still down a ½ liter. Standing there looking at the engine, I attempted to reconstruct past usage that could account for this change. The only thing that had been different was the high speed run last week. However, if the only logical conclusion considered for my oil consumption was resultant of one 15-kilometer pass at high speeds/rpms on the autobahn; I had problems
I departed the station with intentions to stop at the local BMW dealer for the promised top-off now that the oil level was low. Halfway there I realized it was Easter Monday, a European holiday and that nobody would be at the dealer. On to work and thoughts of plan B.
Lunch time and back to plan B, I went out to my car and checked the oil level again. Magic, the oil level is right back where it had been before this morning. Now what? Checked it again and same results. Thought about it again and came up with two other possible explanations.
First possible explanation…the length of time for oil to return to the sump may be longer than some engines and 10W-60 spec oil could be aggravating this duration over lightweight oil. Looking at the plastic tag on the dipstick there is a note that indicates owner should wait a minimum of one minuet after engine is shut off. Not as obvious, it states engine should be at idle for at lease 15 seconds, suspect this substantiates first assumption about drain down time, idle speed would reduce flow to the upper half of engine and enhance drain down.
Back to experience at gas station earlier in day. Don’t know if I idled 15-seconds but was not racing engine either. For certain it took longer than one minuet to add gas so still don’t know if my first assumption is that valid.
Second possible explaination. operating range of engine. Again looking at plastic tag on dipstick it seems to imply that oil check should be done at operating temperatures but not specific. Owner’s manual does clarify this assumption. Back to gas station experience one more time. I had driven less than 10 kilometers from home to the gas station. The last orange ‘pre-warning lights’ had disappeared, the water temp was in the blue range but the oil temp gage was still south of normal range. Maybe a temperature sensitive value in the cooling system opened while I was adding gas and some oil went into the cooler before I checked and/or a combination of both explainations.
It has been a week of checks since this incident and I haven’t been able to duplicate it. Maybe some of you can elaborate or substantiate, but my point to all of this ramblings is this. Appears that something that should be simple i.e. checking your oil level, is not as simple as you thought. I still think a cold pre-start check is most accurate but would not add oil until I followed the owner’s manual. That said however, it appears that the preferred method could be subject to flaws.
Ken

Matte · 24th April 2003, 13:52

Hi Ken,

I don´t know, but the oil in the engine is every where and can show different readings at different times. My suggestion is that u check the oil 10 min after engine shut down every time!! Then u should have an accurate reading every time.

Best Regards
Matte

M'nd · 24th April 2003, 15:19

from what i remember you are supposed to have a warm engine, shut it down wait 1 minute than check the oil level. That is what the instructions are on the dipstick.

kwalls · 24th April 2003, 15:25

Thanks for the reply from M'nd shown below

Quote:

you are supposed to have a warm engine, shut it down wait 1 minute than check the oil level.

However, my whole point is even if you follow those simple instructions as printed on the dipstip you may have problems. Apparently my engine's definition of warm and that printed in the manual were two different things when the false low oil reading happen. If a person didn't double check, as I outlined, you could overfill the system.

apt333 · 24th April 2003, 15:26

A bit off topic, but am I the only one with eyes going bad, or do others have a problem reading the dipstick? That rust color of the plastic tip makes it hard to see the level with clean oil. It takes me multiple times to make a correct reading, and I carry white napkins in the car for background, but changing the color of the plastic would be a big help.

Matte · 24th April 2003, 15:31

I think it´s quite hard to, it takes some time to read the stic correct.

Ken,

If u go with the 10-15minutes u have a warm engine, if we go by the book for one minute the engine is hot

Regards
Matte

kwalls · 24th April 2003, 15:32

apt333
As MIB likes to fun me about age, yes one would think you have bad eyes when checking the oil with CLEAN oil.

However if you were to follow the oil service cycle BMW wants you to use, the oil will become very black before the red light comes on and even us old men can see the level.

Ken

M5Rick · 24th April 2003, 17:55

kwalls - your experience, to some extent, was mirrored in my post of yesterday. I checked and double checked my oil level and process - 1 quart low. My first check was after the car had been off for a couple of days - all oil had to be drained into the sump. Oil was at the bottom line on the dipstick - same reading after two checks with a little warm up - idle 15 seconds and waited for 1 minute to check????? Of interest, I added about a third of a quart and checked the dipstick reading - up about a third of the way above the bottom line - pretty linear relationship. So I am still at a loss with four possible issues: overfill theory, oil filler cap not replaced correctly, design issue involving the tube the our Master Tech explained to me, or some oil system gremlin that I will never understand. What I do know is that I could not have been more cautious in following the process and double checking. I actually wound up doing BOTH a cold and warm engine check! A lot of doubt will be present at my next check!!! This is an important and routine check - it SHOULD be straightforward, but....! Oh well..

schnelleM5 · 26th April 2003, 06:06

Quote:

Originally posted by kwalls
oil check should be done at operating temperatures but not specific. Owner’s manual does clarify this assumption.

This is an excellent question, Ken, and one that I hope someone can definitively answer for us. I had assumed that this meant that the oil is supposed to be checked with the OIL TEMP having reached normal operating temperatures, then idling for 15 seconds, and waiting at least one minute, and this is what I have been doing. It still seems a little strange to check engine oil on a hot engine, something contrary to what I have always thought, but I suppose it has something to do with the special G-sensitive pump system?

Quote:

Originally posted by apt333
am I the only one with eyes going bad, or do others have a problem reading the dipstick? That rust color of the plastic tip makes it hard to see the level with clean oil.

It is indeed a challenge. I use lint free tissues to completely wipe the stick clean and assure that it is completely dry, then re-insert and withdraw as instructed in the manual. To obtain an accurate reading I find that I have to hold it up to a light source to look for the contrast between the dry part of the stick and where the oil level is.

Nybes · 26th April 2003, 07:21

kwalls,
could this possibly have something to do with the scavenging pumps that function durin high lateral-G loading? A hard highway (or bahn) off-ramp just prior to shut down?
anyone have any ideas?
N.

jaj · 26th April 2003, 08:28

Ken

Good to be talking again - hope all is well with you.

I got in the habit of always checking my oil in the same place - my garage after I get home from work. Back into the garage, idle for 15 seconds, shut down, wait a minute, and then check with the dipstick.

That way, it's always fully warm, and its level. I have also checked it cold in the morning before starting out, and I get identical readings, so either method works, as far as I can tell. Personally, I've used the "cold" method since the early seventies, and it's never let me down.

Oil checking is a bit redundant with the M5 - there are those out there that just drive it until the "low oil" message comes up on the dash readout. I figure that if I keep checking, at least I won't get a surprise, but if I mess up on reading the dipstick, there is a failsafe there to protect the machinery.

My 03 is now running the Castrol 10w-60 and in the 1100km since the change, it has consumed exactly none. I'm impressed!

Cheers
JJ