old oil from one engine into another?

[fj610]

So i have redline 10W-40 in my turbo which has a OCI of 15,000kms to comply with the manufacturers warranty. No doubt the oil will still have a high TBN when i dump it, so rather than throwing it out, i had this stupid idea of hygenically transferring it to my work truck which has over 260,000kms. Im thinking why waste top shelf oil which still has a working life?

If this is just wrong, on how many levels is it wrong? On paper, it sounds like a plausable idea no?

 

[Silk]

I change my bike oil at 6 months or 3000km....and use it in a couple of our cars that use oil.

 

[CATERHAM]

How much life do you actually think is left on the RL with 15,000 kms on it? I know oil, particularly ester based syn's like RL are expensive in OZ, but with so little life left in it it's not worth the bother.

 

[demarpaint]

This topic has been discussed a few times over the years. Not many were in favor of it.

I'd use old oil in a beater that burnt oil for top up. I would not add it to fill a sump after an oil change. After 15,000 kms I'd say most oils would be pretty dirty and used up. I'd pass.

 

[Garak]

Originally Posted By: demarpaint
I'd use old oil in a beater that burnt oil for top up.


I would agree. I've seen it done as top up for oil burners, too, with fine results. For a complete change, or nearly complete change, I wouldn't want to use it.

 

[gathermewool]

Originally Posted By: demarpaint
I'd use old oil in a beater that burnt oil for top up. I would not add it to fill a sump after an oil change.


Agreed

Originally Posted By: demarpaint
After 15,000 kms I'd say most oils would be pretty dirty and used up. I'd pass.


I really don't think that there will be much life left, either, but there's one way to find out - UOA. How long would you run the oil in the truck, anyway?

 

[Patman]

I say it depends on how far you're going to drive the work truck on that used mixture. If it's only 5000 more km, then I'd say yes. Redline should easily last 20,000km with room to spare. But if you're going to try to push it another 10,000 to 15,000 more, definitely not.

 

[SteveSRT8]

we have employees with older oil burners that use our discarded synthetic. After a gallon jug of it sits for a week most of the worst particles are settled out, so they are careful not to pour the whole jug, just the first 3/4 or so.

My Brother-in-Law also uses it for cutting oil at the machine shop.

Then we use it for bar oil in our chain saws!

 

[daman]

I would do it if the other vehicle was a real POS.

 

[yaris0128]

Goodness no. Why put one cars dirt into another? If it was a beater your putting it in, sure why not. Other than that, Id never go for it.

 

[gathermewool]

What makes you guys think that the used oil is "dirty"? The filter will keep anything larger than a few microns out of the oil, right?

Originally Posted By: SteveSRT8
After a gallon jug of it sits for a week most of the worst particles are settled out, so they are careful not to pour the whole jug, just the first 3/4 or so.


Could what you guy see settling out be additive precipitating out? There may be some particulate as well, but, based on the few PPM wear metals vs hundreds to thousands of PPM additives, it doesn't make sense that what precipitates out could majorly be "dirt." A fun experiment might be to send off two samples of the same used oil for analysis: one sample whole and another which would be poured from another container to exclude anything that settled out.

 

[berniedd]

As I understand it, additives are dissolved in oil, not suspended as particulates. I'd be persuaded that they can fall out of solution in very cold temps, but at normal room temperatures I'd think they stay in solution.

If you want that used oil to be really cleaner before you pour it into your other engine, why not filter it first? I've done it in the past - I used a filter made of 8 layers of wide tissue paper similar to that used for wiping hands in washrooms. I looked at the oil with a powerful medical microscope before and after it went through my filter. I noted that after filtering, only particles smaller than half a micron remained in the oil.

 

[lipadj46]

Originally Posted By: gathermewool
What makes you guys think that the used oil is "dirty"? The filter will keep anything larger than a few microns out of the oil, right?

Originally Posted By: SteveSRT8
After a gallon jug of it sits for a week most of the worst particles are settled out, so they are careful not to pour the whole jug, just the first 3/4 or so.


Could what you guy see settling out be additive precipitating out? There may be some particulate as well, but, based on the few PPM wear metals vs hundreds to thousands of PPM additives, it doesn't make sense that what precipitates out could majorly be "dirt." A fun experiment might be to send off two samples of the same used oil for analysis: one sample whole and another which would be poured from another container to exclude anything that settled out.


Why does oil turn black? What do detergents do? All the carbon and whatnot that the oil is holding in suspension can settle out.

 

[gathermewool]

The oil turning black doesn't indicate that it's holding an inordinate amount of "dirt" or particulates; it's chemistry, and the color, IMO, is a product of so many things that's it's unreliable as an idicator. If you've got something to counter with, please do. Sarcastic questions don't really get us anywhere.

What's the difference between him running an oil in the old truck with its own contaminants in suspension and the contaminants from another, newer, cleaner engine? If the truck came back with wear, TBN, TAN and all other attributes indicating that the change interval could be extended, then what's to say that those same indications in an oil from his newer car wouldn't mean that it woud be safe to run it in the truck's sump?

 

[SilverC6]

I look at it like this.

All you are saving is a conventional oil change in the receiving vehicle.

That's $12.99 (including filter) depending on the sale at the auto parts store.

Not really worth all the effort.

 

[lipadj46]

Originally Posted By: gathermewool
The oil turning black doesn't indicate that it's holding an inordinate amount of "dirt" or particulates; it's chemistry, and the color, IMO, is a product of so many things that's it's unreliable as an idicator. If you've got something to counter with, please do. Sarcastic questions don't really get us anywhere.

What's the difference between him running an oil in the old truck with its own contaminants in suspension and the contaminants from another, newer, cleaner engine? If the truck came back with wear, TBN, TAN and all other attributes indicating that the change interval could be extended, then what's to say that those same indications in an oil from his newer car wouldn't mean that it woud be safe to run it in the truck's sump?


There are additives in oil to surround and hold particles (products of combustion) in suspension. Those particles can easily fall out of a still solution as they are not soluble in the oil itself. Its just basic chemistry, not everything in used oil is wear metals and additives.

 

[demarpaint]

I've mentioned this story a few times. Back when my E-150 van was new I'd change the oil every 3000 miles, old school, back in the 80's. Flame suit on. My neighbor had a Chevy van that went through a qt of oil about every 200 miles. It was old and beat, he didn't have the money to fix it, or replace it. I gave him my waste oil, he used it for quite a while. I guess we can call it a form of recycling. Would I do it? If I was using that much oil, I certainly would.

If I was worried about dirt, I'd run it through a paint spray sock, or paint funnel screen used for airless sprayers. An engine using that much oil is not something I'd worry about in terms of TBN, TAN or anything else for that matter. I'd just keep oil in it.

 

[lipadj46]

There was the mobil 2 guy too. Perfectly acceptable use of used oil

 

[demarpaint]

Originally Posted By: lipadj46
There was the mobil 2 guy too. Perfectly acceptable use of used oil


At the time I was using M1 10W30, so yes it was Mobil 2

 

[Audi Junkie]

No way. Use the oil till you are finished with it and dump it.