Does adding oil mid-interval extend the change?

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Originally Posted By: bigjl
It probably does.

But I would not do a 15k mile oil change in a BMW.

More than a few BMW engines have serious issues amd I think over long OCI is part of the problem.


Agreed. There is a reason BMW has cut back their oil change intervals on all new cars to 10k miles.
 
Originally Posted By: gtmaster303
Exactly what the title says. My BMW Burns a quart in between it's 15k intervals. Does that mean I can go longer because fresh oil is added?



No. I tried doing a 15k interval in my wife's BMW once, and added a little more than quart during that time as well, and the UOA report did not look very good at all, the oil thickened up considerably and had high oxidation. I'm sure if I continued doing 15k intervals I would not be doing the engine any favors at all. I'm planning on sticking with 6-9k intervals in her BMW from now on.
 
There are so many varnished and sludged BMW engines on the road because of the ridiculous 15k mile OCI recommendation. It’s a shame. 7500 miles would be my limit for that engine and even with that OCI I’d get UOAs with oxidation, nitration, TBN, and TAN tests. I’d also monitor cleanliness around the oil fill hole.

How does it look down the oil fill hole?
 
Originally Posted By: Artem
Originally Posted By: oil_film_movies

As it is, I think BMW did make a change in what it recommends. https://f30.bimmerpost.com/forums/showthread.php?t=868291
and they went to 10k miles (oops moment for them...). Reputation for too much oil breakdown I guess.
Rule of thumb: Go with 15k oil changes if you add at least 2 quarts of oil as you go.
Go with 10k mile oil changes otherwise.




Interesting turn of events... just when all manufacturers are INCREASING OCI even with Di and Turbo high strung 1.5L engines, etc, BMW is going BACKWARDS and DECREASING the OCIs just as oils have reached what is basically a very high level of capability in regards to Lube performance. Hmmmmm....

The real question is, did they do it for better engine protection or did the maintenance department guy have a little chat with the finance department guy at the water cooler and pointed out the extra $,$$$ they could be making with more frequent OCIs??? Lol.

Ah for the Love of Money...


you have it backwards but with same reasoning
. maintenance is included with new cars which coincided with the original bump up to 15k miles. since bmw was paying for it they did less frequent changes.
 
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Originally Posted By: Patman
Originally Posted By: gtmaster303
Exactly what the title says. My BMW Burns a quart in between it's 15k intervals. Does that mean I can go longer because fresh oil is added?



No. I tried doing a 15k interval in my wife's BMW once, and added a little more than quart during that time as well, and the UOA report did not look very good at all, the oil thickened up considerably and had high oxidation. I'm sure if I continued doing 15k intervals I would not be doing the engine any favors at all. I'm planning on sticking with 6-9k intervals in her BMW from now on.

You have a copy of that report? Also what oil and filter?
 
Originally Posted By: oldhp
Expensive car and a long OCI??? Why??? Piece of junk, run it til whenever. Very nice car.......long OCI's. Sorry I don't get it.


Yeah, ditto here ...
 
The reduction in the OCI might not have anything to do with sludge or engine problems. Possibly might be from people using bargain basement products and then running it to the 15k. I haven't owned anything like a BMW so I can't say my maintenance habits would be the same as somebody else.

As for the OP. I believe that makeup can increase the OCI if the make up oil is more like once every 2 months and 2k miles. In this example then I would just change the oil every year. A quart every 15k, for me, is a "no" on extending the OCI. When I was driving 3500-4k a month working 60 miles round trip away my OCI would be 9-12k. Now my daily commute is 4 miles round trip and about 3k a year. With this drive time I do the oil once a year, approx 8-10 months. My oil pan leaks slightly which means during this time period I will add about 1-1.25 qts and so I feel comfortable with this interval.
 
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Even with added oil i wouldn't extend it in my truck at 5,000 miles the make oil is 3 quarts but i don't extend it farther than that
 
One thing to consider about increasing mileage because of adding make up oil, is the % of the total capacity that you are replacing. If you have to add a quart to a 4qt capacity 4 cylinder you have replaced 25% of the oil. On a 7qt BMW 1qt is only 14%.
 
Originally Posted By: AVB
One thing to consider about increasing mileage because of adding make up oil, is the % of the total capacity that you are replacing. If you have to add a quart to a 4qt capacity 4 cylinder you have replaced 25% of the oil. On a 7qt BMW 1qt is only 14%.

Car only takes 5 quarts, but I get what you're saying...
 
Originally Posted By: talest
If you have to add oil mid-OCI, then why is the engine burning or losing oil?

Because that's normal? I don't think there's anything wrong with losing a quart between 10-15k changes
 
During the brief time interval that oil is flowing through the rod and main bearings, most oils will momentarily reach and exceed their thermal breakdown points; and once any oil, conventional or synthetic, has reached its onset of thermal breakdown point, the lighter oil fractions will begin to vaporize, leaving thicker and heavier oil. This will over time, contribute to poor circulation, reduced fuel economy, increased oil consumption, increased wear and increased emissions. This is something to consider if you believe in extended drain intervals.
 
Originally Posted By: gtmaster303
Originally Posted By: AVB
One thing to consider about increasing mileage because of adding make up oil, is the % of the total capacity that you are replacing. If you have to add a quart to a 4qt capacity 4 cylinder you have replaced 25% of the oil. On a 7qt BMW 1qt is only 14%.

Car only takes 5 quarts, but I get what you're saying...
I am used to the old 6 cylinders. I would feel a lot better going 15k on 7qts than 5.
 
Sure it does. Once I think it was a pint of high mileage synthetic that I put into a car that gets bulk and it seemed to perk (or pep) up.

Don't let yourself get carried away though and you need to eventually get contaminants out of the sump by a regular oil change.
 
Originally Posted By: AVB
Originally Posted By: gtmaster303
Originally Posted By: AVB
One thing to consider about increasing mileage because of adding make up oil, is the % of the total capacity that you are replacing. If you have to add a quart to a 4qt capacity 4 cylinder you have replaced 25% of the oil. On a 7qt BMW 1qt is only 14%.

Car only takes 5 quarts, but I get what you're saying...
I am used to the old 6 cylinders. I would feel a lot better going 15k on 7qts than 5.

actually it's a 4 banger for 2012+
2011 was the last year of the base 6 cylinder
 
Originally Posted By: AVB

I am used to the old 6 cylinders. I would feel a lot better going 15k on 7qts than 5.


My wife's BMW takes 7 quarts and it still didn't like that 15k interval.
 
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