Why would a short OCI clean better?

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359
Location
Phoenix, Az
Folks on here often say in order to clean up an engine they'll run a few short OCI's of like 3k before going to a regular OCI of say 5-7k. My question is if oil is still in good shape at 5-7k (or even at 10k), what benefit are you getting from a super short OCI like 3k? Would it be even better at 1k? If the additives, TBN, TAN, etc are all in the good range at 7k then I would think it's doing the same amount of cleaning at 7k as it would at 3k, 1k, etc. No? I'm wondering if we're just catering to our internal warm fuzzies when we think our oil is cleaning way better at an OCI half of what the oil is good for, or is this actually true?
 

rollinpete

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Western Ma.
I would think if your dealing with a dirty abused engine, the additives wouldn't last as long in a long oci thus the reason for a few short ones...
 
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7,059
Location
Wet side WA
Originally Posted By: aquariuscsm
I'm guessing the short "cleaning phase" oci's keep the cleansing additives fresh and strong.
Yah kind of like washing your clothes with clean water and some fresh detergent! But then how many loads of laundry could you get out of a washer if you didn't let it go into rinse. The possibilities could be limitless.
 
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24,467
Location
Dallas,Tx USA
Originally Posted By: JohnnyJohnson
Yah kind of like washing your clothes with clean water and some fresh detergent!
Yep,just like that. Like it you have a filthy rag,and you wash it once until the water gets dirty,then make more fresh water/detergent and wash the rag again. Rinse,repeat until it's clean.
 
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7,923
Location
Hudson, NH
Originally Posted By: aquariuscsm
Originally Posted By: JohnnyJohnson
Yah kind of like washing your clothes with clean water and some fresh detergent!
Yep,just like that. Like it you have a filthy rag,and you wash it once until the water gets dirty,then make more fresh water/detergent and wash the rag again. Rinse,repeat until it's clean.
Good point, the rinse phase is just as important as the detergent/cleaning phase.
 
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4,398
Location
Connecticut
A lot of that old sludge/dirt left behind in the past starts becoming suspended into the newer oil. The sooner it's carried away (by a shorter OCI) the better.
 
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North America
Originally Posted By: rollinpete
I would think if your dealing with a dirty abused engine, the additives wouldn't last as long in a long oci thus the reason for a few short ones...
This. A shorter interval is just making sure the additives aren't used up before the next change. I also like the dirty rag analysis thumbsup
 
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17,501
Location
Clovis, CA
3000 is not a short OCI---1700 is. If the engine is dirty and the oil is cleaning good, then the oil will get dark fast. When the oil gets saturated with dirt and turns dark, change it out and run another short OCI.
 
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592
Location
Florida
Originally Posted By: Merkava_4
3000 is not a short OCI---1700 is. If the engine is dirty and the oil is cleaning good, then the oil will get dark fast. When the oil gets saturated with dirt and turns dark, change it out and run another short OCI.
I'm doing this now with my G20, as I recently replaced the engine with a good used one. Engine was very clean, but I am running "short" OCI of 4K with PP 0w40. It is just now starting to darken at 3K miles, so I'd say this oil could go 6-7K, but I'd rather make use of some of the QSUD I invested in laugh
 
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1,899
Location
Crawfordville FL
I agree. If the oil turns black in 500-1000 miles in a GAS engine, it's most likely cleaning up sludge and should be changed frequently until the time it takes for the oil to darken extends out to 2-3k. I've got 1k on this oci of M1 AFE 0w-20 and when I checked the dipstick this morning the oil had darkened just slightly. Enough to make the dipstick easier to read.
 
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