07-01-2015, 01:02 PM | #1 |
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Oil Burners - Top 30 List
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07-01-2015, 02:51 PM | #3 |
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Today's local newspaper, jsonline.com reports the following: BMW said oil consumption is normal on all engines, and consumption within specifications doesn't mean there's excessive engine wear. The company said some regular BMW motors can consume up to a quart every 750 miles, and M series performance engines can use 2.5 quarts per 1000 miles under certain conditions. The company says it has a service campaign to check and possibly replace some parts in the 4.4 liter V8
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07-01-2015, 07:30 PM | #5 |
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Unless leaking, it is burned, and emitted.
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07-01-2015, 08:46 PM | #7 | |
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The engine is made up of dozens of different alloys to keep weight down. Not just overall weight, but also rotating mass like cranks, cams, rods, cam chains and reciprocating mass like valves and pistons. Each of the alloys expands and contracts at different rates, but they are predictable in certain temp ranges. So, an alloy piston sitting inside a steel alloy sleeved or plated cylinder will warm up (expand) at a different rate than the cylinder, but settle at the expected operating temperature. This is where engineers focus on tolerances, for the most part. While the engine is warming up, it will use the slightest amount of oil around the rings until it's to operating temperature - the entire engine and all its parts. The added benefit (yes, I said benefit) is that there is additional lubrication when warming up. There is nothing wrong with this type of oil use. To prove this point of oil use, 16 liter Cat or Cummins engines burn oil for the same reason and last nearly 600,000 miles before they need a total overhaul. In addition, we have something called crankcase breathers that vent oil from the crankcase into the intake which then burns the vapors in the combustion chamber rather than releasing that crap into the environment. Pressures build up inside an engine due to the pistons moving up and down in the cylinders. Since one piston moves 66 times per second at 4,000 rpm, this vaporizes oil easily and builds pressures fast. Now, think about a race motor or high performance motor that will turn 7500 rpm. Each piston is reciprocating 125 times per second. Oil is needed to lubricate all internal parts, as well as remain as a liquid in this severe environment. To keep pistons/rings from fusing to cylinder walls, most engines have "piston squirters" that purposely spray oil on the under-side of each piston to cool it, and lubricate it. As far as I am concerned, I am perfectly happy with an engine that uses 1 quart, every 1000 miles. My Porsche used 1 quart every 700-ish miles and at the track, it was more like 1 quart per hour. I would tear down my motor each season and find the engine like new - good cross-hatching on the cylinders, rings in great shape, main bearings in perfect shape and tolerance, cams that show zero wear, and so on. To brag that your engine does not use a drop of oil is not so impressive if you own the car and I would bet it's not a high performance motor. Every Japanese engine I owned did not use any oil, but when we tore into them, cylinders needed honing, valves needed replacing, cams showed wear and so on with only 50,000 miles on the clock. For me, a quart every 1,000 miles is to be expected/required on a high-performance engine, or one as complex as what BMW/Merc/Porsche/Audi/etc produces. Even at this rate of use, you will not notice blue smoke in the exhaust and is not a reason for concern.
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07-01-2015, 09:00 PM | #8 |
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07-01-2015, 09:00 PM | #9 | |
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Thank you for the write-up.
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07-01-2015, 09:09 PM | #10 |
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Prior to my 4 BMW's I've owned I had mostly NEW Toyotas, Mazda, Nissans and it is true none of those cars needed to be topped... However the older cars I had did need oil between oil change intervals. Thanks for taking the time to explain in details.
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07-01-2015, 09:17 PM | #12 |
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07-01-2015, 09:46 PM | #14 |
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When I modified my 3.3L flat 6 into a 3.4L, I changed the stock Porsche pistons (Mahle) to custom forged JE Pistons, and the cylinders were changed from nikasil to JB Racing steel sleeved. And the rings were changed to moly rings. Because of this, and the different alloys, I had to modify the assembly measurements. For example, the piston ring gaps had to be larger by .005 in, and the deck height (distance between the top of the piston at top dead center to lowest point of the inside of the head) by .004 in. The point being, it doesn't take much to make a good motor great during assembly and proper tolerances are critical to peak performance.
With all this being said, the last 5 or 6 years or building motors, I always used Rotella T6 oil in every engine, from the very start and every change. That's some high quality stuff...
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07-01-2015, 11:05 PM | #16 |
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Next life I want to be helicopter pilot like you For now, I just have to play with kids' quadrocopter.
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07-02-2015, 09:38 AM | #17 |
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07-02-2015, 05:23 PM | #18 |
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07-02-2015, 09:18 PM | #19 |
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Speaking of clouds, we will use nearly as much oil on start-up of an SBD Dauntless than can be changed in in an X5 35d (not really, but the blue cloud is impressive). The Wright Cyclone engine on ours needs to be walked through so you're not surprised by a cylinder releasing itself by hydraulic lock. Our P-51D will use a couple of quarts just during the time it takes to fly an airshow.
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07-03-2015, 07:19 PM | #21 | |
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07-03-2015, 09:24 PM | #22 | |
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Come out to this year's Great Georgia Air Show in October and see all of them. I'll be one of the air marshals and be glad to show you around. http://www.dixiewing.org Back on topic - we use A LOT of oil, measured by the barrel.
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