Oil shelf life

[ROADWARRIOR]

How long can a partial gallon of Rotella sit before you wouldn't use it in your engine? I've noticed that the oil tends to darken with age.



TIA,

Dan

 

[illflem]

Not sure on Rotella but on drums of Delo it says to use within one year of the date stamped on the drum. My jobber said this is due to additive fallout, it ends up on the bottom of the drum. I would think with a smaller container than a drum just shaking it up would make it fine.

 

[The patriot]

I always figured... . it was in the ground for millions of years.

The addatives are what I'd be cocerned about, like illflem said.

IMO one or two years should be fine, but I aint no expert.

Eric

 

[B9Mile]

Some info here:



http://www.noria.com/learning_center/category_article.asp?articleid=172&relatedbookgroup=Hydraulics



Use the search function at either of these sites and you will get some more info:



http://www.noria.com/

http://theoildrop.server101.com/ubb/ultimatebb.php

 

[pwr2tow]

If you take extended drain intervals into play and what they say..... I would think the oil lasts almost indefinelty, its the additives that wear out from use in the engine not sitting on the shelf..... so what is the correct answer to how long an oil is usable that has never been used???



Ron

 

[pdolan]

Ron:



Read B9's link. This is an excellent resource to identify the various factors (excetp I didn't notice any mention of UV).



Oil may have been in the ground for millions of years, but it is constantly evolving from dead trees, to peat, to coal and finally into gas and oil. Once it is there as crude, the conditions determine if it becomes, napthenic, parafinnic, ashpaltic, etc. This is with little to no oxygen available.



Once the oil is refined and fractionally distilled (separated into the various fractions), the stuff we make lube oils from is called base oil. If you leave raw base oil out in a plate for a few months, it will "dry up" into varnish and sludge. It is the additives that impart some oxidative stability to the base oil.



The old saw that "oil never wears out" is absolute rubbish. The additive package is designed to be used up, and the base oils need to be protected from the degradation which will naturally occur under the severe conditions of high temp, oxidation, fractioning, cracking and chemical degredation found in an engine. If you ever have the opportunity to recieve used lube oil at a re-refining facility, you would find that as much as 10% comes off the top as water, another 20% can be a light fraction (loosely "diesel") and the bottom 10% is asphalt. Unless you are in the habbit of pouring some pavement into your sump, this stuff represents the degredation products of the base oil and additives. This is why I may recommend extended drains (particularly with full synth) but I cannot support the concept of very long or infinite drain.



Sorry to wander off topic, but it is a hot button with me. Additive drop-out is one concern in storage, as is oxidation and acidification. If you can run oil in an engine for 10,000 miles in a year safely - which is a SEVERE storage condition, then sitting on the shelf in your garage is not going ot materially degrade it in two or three.



Pat

 

[illflem]

Pat, I agree with what you say except while in storage the oil doesn't get agitated like it does in the engine, additive fall out is more likely to occur. This shouldn't be a problem as long as you use the entire container of old oil at once, the engine will remix any additive that fell out.

I think the main problem that can occur is when a person wants to save money by buying oil in 55 gallon drums but then takes years to use it. Hard to shake a drum.

 

[pwr2tow]

Geez Pat I don't know how to take your post, at first it sounds like your giveing me hell about extended oil drains and then in the end it sounds like your in favor of them and then oil sitting on the self will last a long time.



I guess I was asking how long it would last on the shelf, while throwing out what some suposed experts say about extended drain intervals.



Ron

 

[DocStressor]

Illflem is right (as usual). The industry recommendation is generally 1 year. Additive drop out is the primary problem. The additives are blended in as an emulsion, which the polar components of the base oil (aromatics, esters, etc. ) tend to keep in suspension. But as the emulsion sits for long periods of time, the detergent/dispersant micelles tend to aggregate and eventually drop out of solution. If you use oil that has been stored for a long period of time, the insoluble additives will be removed by the oil filter. I don't know if they eventually resuspend once they are captured. The rate of oil oxidation in a sealed container should be very low at normal storage temperatures vs engine operating temperatures. The presence of oxidized iron (rust) from a steel container could greatly accelerate oxidation, however. I wouldn't worry as much with oil stored in plastic containers.

 

[pdolan]

Ron:



It is not an easy question to which I can give you a simple, straight answer.



I give everyone sh#t for the idea of infinite drain intervals, but 3k or 6k or whatever is absolute nonsense of equal foolishness. Even OEMs now frequent the 15k recommendation. The point here is that the engine itself is a severe environment for oxidative degradation, additive depeletion and base oil failure. The shelf is not. Yes, additive dropout is a problem, but the proportion of additive precipitating vs. the proportion left i should be no where near the level of depletion from use, and even OEM is happy to see it in the engine for 15k or a year - so the idea that it is unuseable after one year on the shelf is ludicrous.



If you have oil that is a couple of years old, and you are worried about it, agitate it severely and pour it in. The air introduced at that stage is NOTHING compared to what it will see in the engine.



The particles that settle out in the container will be caught by the filter - whether they settled out in the container and got poured in from the bottom or just stayed in suspension. If you can see 'em, the filter will catch them. But, remember that the filter is constantly provided with hot oil being circulated in the engine. The particles will either dissolve into the oil and do their job or get tossed with the filter, but you are NO WORSE OFF either way.



So, don't sweat that fill date on your shelf from the last century.



Pat

 

[illflem]

Pat another problem you're not addressing is say you have a half a gallon of five year old oil and use half of it to top off. Seems that what is left will have too much additive which can also be a problem. Even worse if you have a few year old drum of oil and are pumping it out from the bottom.

 

[pdolan]

Illflem:



For the long time drum guys who may worry about this, the answer is to use a paint mixer on a 1/2" drill and give it a good turn.



If you measure the total mass of additive drop out, I can't imagine it amounting to more than a single-digit percentage of the total mass of additive, so the total variation from "intentded" additive concentration should nver be able to reach +/- 10%. That is well within the range that is "fudged" by some formulators for various reasons.



While the proportion of additives is critical to meet the requirements of the SAE grade and API performance requirements at the time of certifcation, this really only insures that the oil is in that condition on the shelf and when first poured into the sump. Once in the engine, many formulations are depleting additive or even falling out of grade in a very short time (especially cheap VMs). Consider the initial spec as a starting point, and consider that the vast majority of oil isn't even half-way down the road at drain, and you can understand why I don't get too excited about storage issues.



Pat

 

[cmills]

Well if all this is true than I guess my truck is getting a good break-in after rebuild since I have some 4 yr old rotella in it

 

[Cooker]

Wow this was an old thread.

 

[Gary - K7GLD]

"Wow this was an old thread. "



YES, it is - but sorta timely for me, since just this past Sunday, I bought a 6-gallon case of Delo at Walmart - and since it looks like I'm likely going to 12 month oil change intervals, that's a 2 year minimum supply!



With fuel prices rising the way they are - and not likely to ever return to former lows - I figure lube prices will also be seeing similar increases - so stocked up...