A Disturbing Find in a Couple Sample Bottles

[PT1]

Originally Posted By: G-MAN
What you're seeing is what a good quality motor oil normally keeps in suspension so you can drain it out of the engine when you drain the oil. As your sample aged, sitting for months at room temp or lower, the dispersants lost their ability to keep the nasties in suspension and they settled out.

That's my theory, and I'm stickin' to it.

I agree. I have had the same thing happen in a 1 gallon waste oil jug I left in my garage for 2 years. there was a 1" thick layer of "tar" at the bottom.

 

[ekpolk]

Originally Posted By: TallPaul
ekpolk, were these samples actually a year old?

Were the vehicle(s) they came out of newer, older?

Do they have what you would consider fairly clean engines?

How many miles on them?

I can't imagine this stuff being from a fairly new, low mile car.

Now, of course, with the Aerostar consuming a quart every 1300 miles, I am getting a lot of fresh oil in there, including fresh dispersants, so I should be fine with the 5000/1 year OCI.

But it does make me think that I should change the motorhome oil right after a long trip, not just before the next long trip.


Yes, the gunkier sample on the left is, as best I can recall, a little over a year old. It did come from the Prius, which is a clean looking, clean running engine that produces nice UOA results, but with some notable fuel dilution.

That's what's so shocking to me about this -- it certainly implies that leaving oil to sit in an engine for a long period of inactivity is a questionable idea. I'm now all for a change right before any storage.

 

[Alternator]

Looks to me like what you're seeing is what's NOT getting filtered out by the typical full-flow filter.

Whether or not it is suspended or how long it remains suspended, it is circulating in the engine while it is running.

Hope it's not too abrasive.

 

[Pablo]

Originally Posted By: SpitfireS
Just a long shot: could it have anything to do with the plastic container as well?
Plastic is made of "oil", and the added chemicals in the plastic may react with the engine oil?
How about storing the next sample in glass or metal?


I'm not sure about your idea - but I just thought of something. I had a (essentially) sealed 1/2 full quart mason jar with very used motor oil, on my work bench for the better part of 2 years....never jelled up or anything AND I do remember pouring it out. Just some "fines" down at the bottom of the jar. I still think that gel stuff has something to do with moisture.

 

[SpitfireS]

All the oil bottles (motor oil and gear oil) I have are made of HDPE (High Density Polyethylene)
PCV for example has a very poor resistance to Aldehydes, Esters, Aromatic and Halogenated Hydrocarbons, and Ketones.
(found this online)