Weird Oil Blotters

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Oct 22, 2003
By Detroit
I took these blotters yesterday. The top two were taken about five minutes after shutting down a hot engine (18 mile run on a 50 F day). The lower two were taken a couple hours later after the engine cooled some and I jumped on the front bumper a few times in case a film maybe forms on the surface. Anyway, what is weird is that the blotter on the upper left has a much darker ring and center. I pulled the stick and wiped it then redipped the stick before taking the blotters. Also with the top two blotters I noticed as they soaked into the file cards that the lighter one soaked in much quicker than the dark one, which probably took two to three times as long to soak in. I think that has a lot to do with it being darker, but not sure how.  - BTW, this is 10w30 Citgo Ultralife high mileage oil.
it sounds like hot oil soaks into youre paper easier than cold oil?
Well, both top row blotters were at the same time and hot. Top right does not look significantly different from bottom row which was a couple hours after I parked the truck. I do think the upper left looks much worse that the others. In fact, I might be inclined to change it out if the others came up like the upper left blotter.
TallPaul, The phenomenon is very well known in thin layer chromotography. Ideally, the insolubles should not migrate away from the site of the original sample. The different between the top left sample and the others is the rate at which the oil diffused out. The slower the flow, the less suspended insoluables will flow. The other three samples had flow that was thick enough to carry the some suspended particles in the bulk flow. This is no different from washing your driveway with the hose at low flow verses high pressure. The higher the flow, the more "stuff" that will be carried along.
To me, living in always warm Florida...although the top one does have a dark center, it looks as though there is still plenty of the additive life left...but then the others look like the oil is on the way out with the dark center expanding and less defined. But then you live in Detroit, and as stated these were taken at different times, different temps. TallPaul, its in reading your posts that I became interested in blotters(gosh, I wish there was a blotter section here at BITOG, so we could all compair and learn together)...Im still learning and observing, but I try and stay consistant with my blotter samples and have noticed big differences in blotters taken in the same day from the same vehicle. Taken out of context(not having seen any of the other blotters from this OCI)this blotter doesnt mean much, but compaired to the rest of the OCI's samples Im sure it does. But the good news is, you can still keep going on this OCI! And thats all I really use it for, this poor mans "oil life monitor". Id say consistancy and temperature is the lesson here.
I will be doing a UOA in a few hundred more miles and will leave it in longer if suitable. I am looking for lead as the last two UOAs had 476 ppm lead followed by 114 ppm. Hoping it has gone down. Funny thing, I have been doing blotters for a couple years now and always do two at a time and never had this result. Well, maybe the one file card was a bit thin or something.
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