Burning rate in various stages of one OCI

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I bought my 2009 Nissan Maxima with 103k miles when it had 80k miles. It was one owner and in pristine condition. %95 of maintenance was done at a Nissan dealership in PA. I have at least 15 documented OCIs most of them done at the dealership ship with what listed as "Nissan 999BK05w30NW" oil with Nissan filters.
I've done DIY oil changes since I got it using Nissan filters. Used Amsoil SS 5w30 once, 2 PUP 5w30, once or twice M1 0w40 and last 2 OCIs with M1 EP HM 5w30.
It "burns" about half a quart every 2k miles or so. PUP was fastest to burn. Which steered my away from it entirely.
But what I noticed lately that the rate of burning goes down the farther I go in one OCI(and rather consistent in each OCI). Example I'm now at 2k this OCI and it seems the rate of burning is less than say during 1st 1k miles.
Any explanation of that?
 
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Are you sure that you're not over-filling it, and it's pushing a lot of vapor into the crankcase vent system?
 
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In ancient times (late '60s early '70s) my Ford 289 V8 seemed to burn more oil towards the end of an oil change interval. I had always thought that was because the viscosity wasn't staying in grade.

But then again I have no doubt that oils have changed a lot since then.
 

mahanddeem

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Are you sure that you're not over-filling it, and it's pushing a lot of vapor into the crankcase vent system?
It's not easy to overfill it. I have a high ramps under front tires and the drain plug is in the back of the pan and wait for the last few drops then close the plug. Then it fills with a complete jug of 5 quarts
 

ZeeOSix

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But what I noticed lately that the rate of burning goes down the farther I go in one OCI(and rather consistent in each OCI). Example I'm now at 2k this OCI and it seems the rate of burning is less than say during 1st 1k miles.
Any explanation of that?
The first thing that needs to be verified is if the dipstick is linear. I have done this procedure on a couple of my vehicles, and it can be done when an oil change is done.

Start out with the car level (and springs settled from driving after the oil change) and the oil level showing on the "Low" or "Add" mark on the dipstick when the oil is cold. Then use an accurate graduated container and add 1/4 qt (8 oz) of oil. Check the dipstick level 20 minutes after adding the oil, and note the dipstick level. Do the same thing with 3 more 8 oz adds, and note the level on the dipstick. Does each 8 oz addition of oil result in a corresponding 1/4 rise in the dipstick between the "Add" and "Full" marks on the dipstick (assuming the distance between them represents 1 quart)? If so, then the dipstick is pretty linear ... if not, then that could make one to believe the oil burn rate is non-linear.

If you find the dipstick is linear, then you can better determine if the change in oil burn rate is real or not.
 
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My Lucerne does this. It uses about 1/2 qt in 2500 miles over the course of a year. Most of that is in the fist six months. It's done this with VFS and VFS HM. I wonder if the temperature has anything to do with it. I always do annual changes in mid April, so the first six months is during the warmer months 🤷‍♂️
 
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A previous car I owned had the opposite effect, it would use more oil after 5,000 miles. A LOT MORE. Almost nothing up until 5,000 miles...maybe half a quart. Then it would drink it to the tune of a couple more quarts between 5,000-7,000 miles. Never quite understood it but I ended up keeping my intervals to 5,000 miles after going through that...then it just got worse anyway as the car started racking up the mileage.
 
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A previous car I owned had the opposite effect, it would use more oil after 5,000 miles. A LOT MORE. Almost nothing up until 5,000 miles...maybe half a quart. Then it would drink it to the tune of a couple more quarts between 5,000-7,000 miles. Never quite understood it but I ended up keeping my intervals to 5,000 miles after going through that...then it just got worse anyway as the car started racking up the mileage.
Same experience here...
 

mahanddeem

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The first thing that needs to be verified is if the dipstick is linear. I have done this procedure on a couple of my vehicles, and it can be done when an oil change is done.

Start out with the car level (and springs settled from driving after the oil change) and the oil level showing on the "Low" or "Add" mark on the dipstick when the oil is cold. Then use an accurate graduated container and add 1/4 qt (8 oz) of oil. Check the dipstick level 20 minutes after adding the oil, and note the dipstick level. Do the same thing with 3 more 8 oz adds, and note the level on the dipstick. Does each 8 oz addition of oil result in a corresponding 1/4 rise in the dipstick between the "Add" and "Full" marks on the dipstick (assuming the distance between them represents 1 quart)? If so, then the dipstick is pretty linear ... if not, then that could make one to believe the oil burn rate is non-linear.

If you find the dipstick is linear, then you can better determine if the change in oil burn rate is real or not.
I disagree with this theory. Because I top off whenever oil level is around mid level between H and L on the dipstick. So I'm always reading the upper half of the reading area on the stick.
 
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Have you tried just putting 4.5 qt in and see what happens? I've had vehicles that I discovered would consume oil whenever kept on the full mark but would cease if allowed to run about the midpoint of the safe zone. I just started filling them to that level during an OCI.
 
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Are you sure that you're not over-filling it, and it's pushing a lot of vapor into the crankcase vent system?
When you put the above question together with @Gene K's suggestion (#12, right above), you have to wonder if the dip stick is correct.

In my experience, oil shouldn't burn off early and then stop. But if it's overfilled (even if it's correct on the dipstick) it could.

I think Gene K's suggestion of starting off "half a quart low" is a good one. You'd just have to watch the level a bit more carefully.
 

ZeeOSix

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I disagree with this theory. Because I top off whenever oil level is around mid level between H and L on the dipstick. So I'm always reading the upper half of the reading area on the stick.
How much oil does it take to go from the mid L to H point to the H mark? Have you ever verified it takes a quart to go from L to H ?

Do you check oil level with the car parked in the same level place when it's always cold ?
 

mahanddeem

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How much oil does it take to go from the mid L to H point to the H mark? Have you ever verified it takes a quart to go from L to H ?

Do you check oil level with the car parked in the same level place when it's always cold ?
1/2 quart
Yes
 
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