Which is better - clean *or* dirty dipstick ?

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5
Location
Indiana
I have read and searched but I haven't found a consensus opinion about this subject. Does a clean dipstick (after 1000 - 2000 miles) mean that the oil filter is doing a great job (and therefore a dirty dipstick means that the filter isn't doing it's job anymore) ? *OR* Does a dirty dipstick mean that the oil is doing a wonderful job of keeping the crud in suspension (and therefore a clean dipstick means that the oil isn't doing it's cleaning responsibilities and crud is building up in the engine) ? If a clean dipstick is better, then can we assume that an oil (or filter only?) change is needed when the dipstick starts looking dirty and as long as it stays clean (I am assuming the use of a quality oil with appropriate cleaning capabilities) then the drain interval can be extended ? I'm hoping that the answer to this is NOT "it depends", or, "only an oil analysis can determine still okay or not okay". What's my goal, always having a clean dipstick *or* being elated that mine is dirty ?
 
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1,933
Location
Oklahoma
Quote: "I'm hoping that the answer to this is NOT "it depends", or, "only an oil analysis can determine still okay or not okay"." With that said,I am afraid you will not get the answers you want. I beleive you have answered your own questions other than the category "depends" falls under . [Smile] [ September 12, 2002, 01:53 AM: Message edited by: dragboat ]
 
Messages
3,683
Location
Chattanooga, TN
Mine is always amber at my intervals which are from 5000-12,000 miles depending. However, on the dipstick on one or two cars it looks dark, however, I have taken to placing a few drops on an aluminum foil type cardboard and observing it and letting it dry to look for dirt and rubbing between finger before and after it dries. So, even though mine may look dirty on the dipstick when placed on the foil type background it looks pretty clear/amber after all. I think very dark brown is fine. thick sludgy color black would be bad for me.
 
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2,077
Location
Cordelia, CA
One thing I had thought of, when I noticed the 0W40 getting darker, more quickly than the 5W30 had, is that the 0W40 seems to cling better, and is probably thicker(more depth and so a deeper shade), so it probably just seems like it is getting darker.
 
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3,321
Location
Bolivia
Agreeing with all said, also take into consideration when changing brands that one oil might be cleaning out what the other left behind. Also, Diesel oil will be dark within a few minutes. And oil that has oxidized has changed to a rubber-type compound that clings more than oil (but doesn't lubricate). Incomplete combustion or too rich a mixture will also darken oil.
 
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874
Location
Pacific NW
If it's black & stinky in 500miles you have a problem. If at 3000 it might be normal for that engine, but you'll be thinking about changing it anyway. An eyeball test is no better than a hint and it might not show up when you need it. You can have good but ugly looking oil, or, especially with by-pass filtration, you can have pretty but spent oil. Basically, you said it. "only an oil analysis can determine still okay or not okay." If you're set on using just your eyes, remember, visible and invisible contaminants don't have to increase at the same rate. Worse, oil additives can be depleted before the oil turns black. Full-flow filters won't catch soot so oil color doesn't mean your filter is spent. You could replace it and there'd be no visible change. David
 

GACrabill

Thread starter
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5
Location
Indiana
OneQuartLow : "You could replace it and there'd be no visible change." Conversely, if the dipstick oil is turning darker and only the filter is changed...and then the darkness disappears...does that mean that the old filter had reached it's limit ?
 
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874
Location
Pacific NW
quote:
Originally posted by GACrabill: OneQuartLow : "You could replace it and there'd be no visible change." Conversely, if the dipstick oil is turning darker and only the filter is changed...and then the darkness disappears...does that mean that the old filter had reached it's limit ?
That's what I meant. Replacing the filter would not change the visible color appreciably since the color is an effect of suspended particles smaller than most filter pores. Installing a by-pass filter would change it more but from what I know you'll never go from dark to amber without a refining process. The question I'm hearing is: "can I tell if my filter is bad by the color of the oil". The answer would be no. I do think someone should make filters with little red "I'm dead" indicators on them like sink-mount water filters. Something based not on flow, but on actual percentage of time spent in by-pass. It's annoying not knowing when they're dead without cutting one open. Do dead witches float? David [ September 12, 2002, 06:06 PM: Message edited by: OneQuartLow ]
 

Al

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19,168
Location
Elizabethtown, Pa
quote:
Originally posted by TooSlick: Oil primarily darkens due to exposure to heat, oxidation and reactions with combustion by-products, including partially burned fuel and oxides of nitrogen and sulphur. These reactions are the "precursers" that lead to the formation of organic acids. Generally speaking, if the oil is turning darker in a particular application, you are getting more "blow by" past the piston rings into the crankcase. You will find increased levels of oxidation/nitration and more TBN depletion in these cases. For a given application, cleaner is better....
I would tend to agree with this. Over many years, vehicles where the oil stayed cleaner- engines used less oil and ran better longer. Kind of subjective, just my experience. [ September 12, 2002, 08:44 PM: Message edited by: Al ]
 
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5,785
Location
Dixie
Oil primarily darkens due to exposure to heat, oxidation and reactions with combustion by-products, including partially burned fuel and oxides of nitrogen and sulphur. These reactions are the "precursers" that lead to the formation of organic acids. Generally speaking, if the oil is turning darker in a particular application, you are getting more "blow by" past the piston rings into the crankcase. You will find increased levels of oxidation/nitration and more TBN depletion in these cases. For a given application, cleaner is better....
 
Messages
349
Location
Quebec, Canada
quote:
Originally posted by TooSlick: Generally speaking, if the oil is turning darker in a particular application, you are getting more "blow by" past the piston rings into the crankcase. You will find increased levels of oxidation/nitration and more TBN depletion in these cases. For a given application, cleaner is better....
TooSlick, Does this mean that my Delvac 1 5W40 in my Protege was wearing out faster than my Tech2000 10W30 since my Tech2000 looked cleaner only after 2000km? And after my drain interval, my Tech2000 looked dirty, but nothing like Delvac 1 after 3000km. Regards, Oz
 

MolaKule

Staff member
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21,602
Location
Iowegia - USA
As long as the engine is clean, the oil on the diptstick can be as dark (but still fluid) as it has to be. Regarding blow-by, I find that oils like Amsoil 5W30 HDD allow more blow-by than Amsoil 10W30 ATM, especially in my Nissan Frontier. I think its a viscosity thing.
 
Messages
3,683
Location
Chattanooga, TN
I have seen filters fail in the drainback valves/gaskets but I have yet to see a filter become so full of contaminants (the RX treatment excluded) that it has gone into bypass permanently. I just don't believe that there are enough particles caught by the ave filter in even an extended drain to fill one up as someone mentioned above for a need to have an indicator of usefullness built into the filter. Guess I live in the wrong climate (not dusty enough) or whatever.
 
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3,321
Location
Bolivia
Spector..... that is hard for most of us to determine. Cars don't have before and after pressure guages (although they should). The amount of filter media in a filter varies wildly, as can be seen by many of the studies posted, plus the one on my site. Also different oils clog filters differently. Going back to color, A customer of mine stopped using Delo because he bought 10 new Scania trucks. The Brazilian truck dealer said he HAD to use Lubrax Top Turbo 15w40 - "the only approved oil" by them. That's a lie, but he believed it. Last week he was bragging how good the oil was because at 20,000 km it was still bright yellow. I sent it to the lab: It came back as 12.1 visc, 2200 ppm calcium, 600 ppm of Phos and 700 zinc, high wear metals (no dirt). Leave out the additives and it is clearer, leave out the calcium and it leaves the crud in the engine.
 
Messages
690
Location
Fort Smith, AR
I've wondered about this too. But my observation is that it may be more a reflection of the engine than the oil. I've slowly switched 4 vehicles over to synthehic in the last year, using several brands in the process. I've noticed that the oil darkens in each at about the same mileage, regardless of brand or whether I'm using dino, blended, or syn. I don't give it any thought anymore.
 
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