I have saved used oil [5,000 miles old] for use as a rinse after performing an engine flush, piston soak etc. Question is will it degrade in some way after a couple of years of storage and become somewhat un-usable for my purpose? Become more acidic? or....
Does stored used oil continue to degrade in the bottle?
- Thread starter WobblyElvis
- Start date
No it doesn't really get acidic on its own. Oil gets acidic when exposed to heat, the products of combustion and the mixed sulfur oxides from fuel, and even then it will happen only after the TBN is depleted. Much like "old" oil in the pan, it is what it is until the next time the engine is operated.
But you keep old oil for a couple of years?
Gosh, I never even considered rinsing with oil after a flush or soak. I just always drain it and change the filter, fill it, check for leaks, and move on.
I’ll revise what I posted earlier, if there is fuel in the oil that can harm the VM over time.
Patman
Staff member
Why bother saving old oil for those flush situations when you can just grab some cheap oil on sale for that purpose? And how often are you doing these engine flushes anyway? (And why?)
You are far more likely to put debris into the engine by doing this rather than the least expensive new oil you can find.
Didtch the used oil (dispose of it properly of course) and just change the oil and filter after a piston soak. Done.
Sounds like an opportunity to heat the garage with an antique oil heater
I use a modern one from vevor.
Carlostrece
$100 Site Donor 2025
Personally I think flushing is unnecessary, but if you're going to the trouble of a flush and rinse, why not just buy the cheapest motor oil you can find on sale of any brand, any viscosity (within reason). If you're not picky about brand, viscosity, or type (syn, blend, conv) then you can find some great sales with very low prices. Especially if you're not in a hurry and can wait for sales.
Then you'd have cheap low cost new oil for a rinse.
Then you'd have cheap low cost new oil for a rinse.
Carlostrece
$100 Site Donor 2025
Yes. That's a good use for used conventional motor oil, but does synthetic oil burn well?
15+ years ago my mechanic heated his shop with an oil burning stove that burned used motor oil. He said conv oil burns well, but syn does not. So he burned the conv oil and brought syn to a recycler. I don't know what he did with blend oil.
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Group III synthetics (which most are) will burn identically to a Group I or Group II conventional oil since the molecules are essentially identical. Group IV bases (PAO) burn just fine too.
An ester Group V will burn great too but there generally isn’t much of that in the mixture.
Carlostrece
$100 Site Donor 2025
Huh. I wonder why my mechanic thought his stove wouldn't burn my used Mobil One 10w30 from my Jeep. I wonder if he just assumed it wouldn't burn well, or if he actually tried it with poor results. Would it matter if his stove was an old antique vs modern? This was 20 years ago. His stove might have already been old back then.
Carlostrece
$100 Site Donor 2025
BTW - Wouldn't one or two quarts be enough for a rinse? If buying 1 or 2 quarts of new oil on sale, it's not much money. So I don't see a reason to use used oil for rinsing.
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Even if it were $10, isn't it like throwing $10 out the window while driving on the highway
There is alot of "Voodoo thinking" on here.
That wouldn’t be the first of those notions I’ve heard.
Patman
Staff member
Then again spending money on engine flushes is throwing money out the window too…
I have burned some waste oil, group III in my waste oil burner. Seems to burn great.
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