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  #1  
Old 08-14-2019, 07:15 AM
RDAN RDAN is offline
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Mein Auto:
oil consumption

2006 Z4si 105,000 miles
What is a "normal" oil consumption to expect with
Mild driving/short local trips
RPMS mostly under 4.5K
Always used BMW oil until recent switch to Mobile 1 same viscosity
Thanks
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Old 08-14-2019, 07:35 AM
Autoputzer Autoputzer is online now
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The plot thins... literally.

BMW's LL-01 5W-30 has a higher viscosity than most 5W-30's. It's almost a 5W-40. BMW's LL-01 5W-30 is also made by Shell, from natural gas in the gas-to-liquid (GTL) process. GTL oils have a lower volatility that other synthetic oils. So, yeah, it's possible that changing your oil brand would cause an increase in consumption.

Another cause of oil consumption can be varnish on the piston rings. Varnish (a brown film of broken down motor oil) can cause the rings to stick to the piston in their closed position, instead of in their open position pushing against the cylinder walls. Modern engines use low-tension rings which push against the cylinder walls with less force and friction, making them more vulnerable to piston ring sticking. If this happens, you get low compression and massive oil consumption as if the engine was worn out. But, all the metal is still there. Mobil 1 5W-30 doesn't meet the stringent BMW LL-01 requirements, and is therefore more likely to allow the formation of varnish. Mobil's Super Synthetic Euro 5W-40 does meet BMW LL-01, though.

Newer BMW's are turbocharged, and turbochargers can be a source of oil consumption. My 535i, now at 59k miles, burns a about 800ml in 8k miles. Any car will consume more oil at 100k miles than at 10k miles. Over the decades, I've seen my cars start using more oil around 75k miles, and that even with using synthetic.

Your car doesn't require LL-01. But, "virgin in the volcano" (it might not be necessary, but it can't hurt), and "bomb the orphanage" (solve a problem early, before it is a problem) applies here.
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Last edited by Autoputzer; 08-14-2019 at 05:01 PM.
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Old 08-14-2019, 08:42 AM
RDAN RDAN is offline
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Mein Auto:
I only have abut 4K on the Mobil 1.
I will change back at next oil change.
In those 4K it was down 8oz from full.
Thanks for the info provided. Do you think 1 quart between oil changes is much for this vehicle?
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Old 08-14-2019, 04:32 PM
Autoputzer Autoputzer is online now
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Quote:
Originally Posted by RDAN View Post
I only have abut 4K on the Mobil 1.
I will change back at next oil change.
In those 4K it was down 8oz from full.
Thanks for the info provided. Do you think 1 quart between oil changes is much for this vehicle?
Eight ounces in 4k miles (16k miles/quart) on a 100k+ mile engine is about a good as it gets.

At 90k miles, my Chevy Cobalt SS only burnt ~300ml in 8k miles. But, at the 117k mile oil change it was up to ~800ml in 8.4k miles.
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Old 08-14-2019, 07:30 PM
Andyz4 Andyz4 is online now
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RDAN I have the same year and model as you but 120k miles. Running Mobil 1 5w30 changed at 5k intervals, using about 1/2 qt between changes, and may use more if there are multiple track days. I think your consumption is excellent. Even a "perfect" engine will naturally lose oil during combustion process through vaporization and as trace oil is burned off cylinder walls.
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Old 08-15-2019, 07:00 PM
RDAN RDAN is offline
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Thank you both for your reponses.
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