Soot and oil level. Question.

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Does the accumulation of soot have an affect on the oil level? I added 1/2 liter this past weekend and the oil is only ~1.5k miles from needing a change so you can imagine it's fairly sooted up at this point. I was wondering if the extra surface tension of the soot particles could have had an affect of pulling down the oil level by about .25 liters (I was ~.25 liters short from full when I did an OC @6.5k miles).
 
Soot increases viscosity and does not decrease the volume afaik.

Does your manual call for an oil change at 6.5k?

My MB calls for a 5k oci but I usually do it at 4k. My Benz is way older than your BMW though and soots up the oil pretty quickly.
 
Originally Posted By: Oldwolf
Soot increases viscosity and does not decrease the volume afaik.

Does your manual call for an oil change at 6.5k?

My MB calls for a 5k oci but I usually do it at 4k. My Benz is way older than your BMW though and soots up the oil pretty quickly.


Actually my car suggests an OCI anywhere from 9k-12k miles, but I did a change at 6.5k miles and the OBC has counted down to 1.6k miles for the "first" change (The ODO is at 11,5xx miles).
 
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The variations in level are likely due to temperature variations or slight changes in level. That's why I don't fool around with adding oil until it's at the add mark. That saves overfilling. Plus, many engines prefer the level down from full a bit and will not use oil at a slightly lower level. You keep adding topup, it keeps using it. Some advantages also, such as bolstering the additives a bit. Anway, use some standardized formula (according to the OM), such as always hot (with 10 minutes draindown) or always cold, always parked on the same spot, etc., to get accurate levels every time.

As a tech, I've had to fool around with oil consumption complaints and applied some of what I learned to my own equipment.

To answer the original question, soot doesn't increase volume to any dipstick-measurable extent, though it will increase viscosity as it builds up.
 
Originally Posted By: Jim Allen
The variations in level are likely due to temperature variations or slight changes in level. That's why I don't fool around with adding oil until it's at the add mark. That saves overfilling. Plus, many engines prefer the level down from full a bit and will not use oil at a slightly lower level.

To answer the original question, soot doesn't increase volume to any dipstick-measurable extent, though it will increase viscosity as it builds up.


I agree. I check the oil every fillup (~2 weeks) and in this case I was getting the same level every time for the past month or so, and being that I had a bottle which was about 1/2 full so knowing I was at the 1/2 mark or just below I decided to pour it.
 
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