Should I leave a little used oil in? ( DNewton3 )

Status
Not open for further replies.
Joined
Dec 31, 2016
Messages
10,136
Location
Waco, TX
I've got 11,000 on some Warren 5W-30 Semi-Syn, and it still "looks" good... (I change a lot of oil in "abused" vehicles - this stuff 'looks like new' compared to some stuff I drain!)

With Texas heat getting hotter and me doing more and more trailer towing, I'm thinking it's time to change the oil.

I have read some of DNewton3's posts, and he backs his words up with science. For example:

Originally Posted By: dnewton3

Additionally, Ford/Conoco proved this as well. Wear rates DROP as the OCI lengthens.
Check out SAE 2007-01-4133; buy it and read it! Ford tested wear at 0 miles, 3k miles, 5k miles, 7.5k miles, 10k miles and even 15k miles; the wear rates were highest upon the OCI and least after 15k miles!

Generally, there is a parabolic curve that is associated with wear rates. The are slightly higher initially, drop down to nearly nothing, and then escalate again after the oil is compromised past its point to deal with contamination.

The "uptick" in wear is due to the tribochemical barrier being removed by the "fresh" detergent package upon installation. Yes - believe it or not, too much of a good thing is a bad thing. Now, DO NOT read too much into this; I'm not saying it will kill any engine. But what I am explaining, and what is abundantly clear in UOA data as well as supported directly with the SAE article, is that the wear is HIGHER upon the initial OCI, because the cleaning additives actually remove the boundary layer that protects the metal parts. Don't believe me? Read the whole article. And review my "normalcy" article as well; there is CLEAR data that shows the wear rates drop the further out you get from an OCI event.

I stand by what I state; it's true despite what rhetoric may contradict it.

Please provide a link to your referenced article; I'd like to read it.

For reference of my claims:
http://papers.sae.org/2007-01-4133/
and my article:
http://www.bobistheoilguy.com/used-oil-analysis-how-to-decide-what-is-normal/


So, I'm thinking of changing the oil to reduce varnish and possible deposit buildup in the engine (not worried about wear too much at all)

My Question:
Should I leave a little used oil in?
1 quart?
2 quarts? (sump & filter holds 6)

It would add "new add pack stuff",
and some new detergents, etc. ...

...but would leaving a little "old" oil help with the "tribochemical barrier" not getting removed?
 
This is probably another job for Universal Answer B Man (Nobody Knows) but I'd guess not.

I THINK the used oil (from your refs, and from what I vaguely remember reading) isn't the main thing here, its the established tribofilm. Used oil is mostly relevant because of what isn't in it, and it'll be swamped by the new stuff.

If you're concerned about varnish formation then the only practical way to avoid that is to get most of the oxidised oil out of there.

Or I'm wrong. Could easily be.
 
Last edited:
Id do a UOA on the oil but change it out. Get TAN and TBN readings. I dont think leaving old oil helps reduce varnish and deposit buildup.
 
I'm sure I'm "over thinking" this - I should just change the darnn oil already!
grin.gif
grin.gif
grin.gif
 
That paper keeps getting trotted out as proof of something that the paper never tested nor demonstrated.

They took a bunch of used oils, some of which were utterly shagged, had thickened excessivly and had poor TBN.

Then they use a contacting surface tribometer and measured the establishment of the tribofilms with new and progressively used oil. The used oil formed tribofilms on fresh metal surfaces quicker than fresh.

This is entirely to be expected, as the first part of the laying down of tribofilms involves partial destruction of the ZDDP/Mo into more reactive species...some additive companies put a lot of different elemental "variaties" in so that there are different points of activation.

So the oil with the most already partially reacted species in it produced the best tribofilms the earliest...exactly as expected.

The Used oil, excessively thick, wiht no TBN to speak of was not necessarily the best oil to have in the engine. Extrapolating the limits (surface tribometer) of this study INTO that realm is really stretching the bow a bit (well a lot).

And at OCI, the quote that you have provided assumes that ALL of the tribofilm is removed to fresh metal (not true, never seen anything on that).

As to the thought process...

https://bobistheoilguy.com/forums/ubbthreads.php/topics/4060600/1
 
Leave the filter for a week or two after changing the oil. Then change the filter and top up. Any partially activated films will be deposited by then and the "new" oil will be starting to activate
smile.gif
 
Broc, Dyusik, and Mr Nice...that is where I am at (can't with the Colorado, it's dealer service under warranty)...change oil on partially blinded filter, so any bottle contaminants are picked up...change filter mid OCI.
 
I'm staggering my oil and filter change. 50% Off-Set.

Just say I decide on a 6 month OCI. I do the oil now (0 M), filter in 3 months (3 M), oil again in another 3 months (6 M), filter again in another 3 months (9 M), etc.

Which reminds me, it's time to swap my filter soon, it's done about 11,500 KM (7,100 miles). The SynPower oil has done about 7,500 KM (4,600 miles) and is still looking very good. OK, so it's not exactly 50% off-set, but you get the idea.

I always top off with the same oil that is already in the sump, when I do a filter change. As my car takes 4.5L, but I buy 5 L containers. It doesn't consume a noticeable amount, so it's nice to give it a dose of the fresh stuff half way through.
 
My 6.6 Duramax will take 12 liters of oil if I let it drip the last drop, facing up hill overnight. In goes the new oil and after 15 minutes of running it will drain out almost as black as the old oil. This tells me that there is a lot of residual oil in the engine despite my best efforts to drain it all out.
Gasoline doesn't blacken the oil like Diesel, so you can perform this experiment with oil drained from a gasoline engine.
 
Originally Posted By: Linctex
I've got 11,000 on some Warren 5W-30 Semi-Syn, and it still "looks" good... (I change a lot of oil in "abused" vehicles - this stuff 'looks like new' compared to some stuff I drain!)

With Texas heat getting hotter and me doing more and more trailer towing, I'm thinking it's time to change the oil.

I have read some of DNewton3's posts, and he backs his words up with science. For example:

Originally Posted By: dnewton3

Additionally, Ford/Conoco proved this as well. Wear rates DROP as the OCI lengthens.
Check out SAE 2007-01-4133; buy it and read it! Ford tested wear at 0 miles, 3k miles, 5k miles, 7.5k miles, 10k miles and even 15k miles; the wear rates were highest upon the OCI and least after 15k miles!

Generally, there is a parabolic curve that is associated with wear rates. The are slightly higher initially, drop down to nearly nothing, and then escalate again after the oil is compromised past its point to deal with contamination.

The "uptick" in wear is due to the tribochemical barrier being removed by the "fresh" detergent package upon installation. Yes - believe it or not, too much of a good thing is a bad thing. Now, DO NOT read too much into this; I'm not saying it will kill any engine. But what I am explaining, and what is abundantly clear in UOA data as well as supported directly with the SAE article, is that the wear is HIGHER upon the initial OCI, because the cleaning additives actually remove the boundary layer that protects the metal parts. Don't believe me? Read the whole article. And review my "normalcy" article as well; there is CLEAR data that shows the wear rates drop the further out you get from an OCI event.

I stand by what I state; it's true despite what rhetoric may contradict it.

Please provide a link to your referenced article; I'd like to read it.

For reference of my claims:
http://papers.sae.org/2007-01-4133/
and my article:
http://www.bobistheoilguy.com/used-oil-analysis-how-to-decide-what-is-normal/


So, I'm thinking of changing the oil to reduce varnish and possible deposit buildup in the engine (not worried about wear too much at all)

My Question:
Should I leave a little used oil in?
1 quart?
2 quarts? (sump & filter holds 6)

It would add "new add pack stuff",
and some new detergents, etc. ...

...but would leaving a little "old" oil help with the "tribochemical barrier" not getting removed?


No. Leaving dirty oil in will just contaminate the new stuff. Extend your oci instead
 
Just change the oil and filter man.
You already put 11000 on it and that filter is shot unless its an Ultra.
You worry too much.
 
Originally Posted By: Dyusik
Or depending on the filter just leave it alone and change it next time...


I already run oils filters 2x OCI's... I have picks on here of a Fram Tough Guard that just did 15,000

Originally Posted By: Dallas69

You already put 11000 on it and that filter is shot unless its an Ultra.


I haven't had any oil filter failures in many years. It's a Wix (Affinia) and I seriously doubt it's "shot".
 
No. In fact PSA (that would be Peugeot/Citroen) even published bulletin on how accurately change oil on 1.6 16v HDI (modern common rail diesel).
In short, if procedure is not followed to the letter, on OC some oil would remain in engine resulting in accelerated (new) oil thickening and engine (turbo actually) damage.

Eventually oil would be too compromised to take the longer Euro OCI and turbo oil feed pipe would get clogged. This would happen over just several consecutive OCI if not performed as noted.
 
Originally Posted By: chrisri
PSA even published bulletin ...procedure is not followed to the letter, on OC some oil would remain in engine resulting in accelerated (new) oil thickening and engine damage.


Curious.
 
Originally Posted By: chrisri
No. In fact PSA (that would be Peugeot/Citroen) even published bulletin on how accurately change oil on 1.6 16v HDI (modern common rail diesel).
In short, if procedure is not followed to the letter, on OC some oil would remain in engine resulting in accelerated (new) oil thickening and engine (turbo actually) damage.

Eventually oil would be too compromised to take the longer Euro OCI and turbo oil feed pipe would get clogged. This would happen over just several consecutive OCI if not performed as noted.



This sounds a little plausible, until one thinks back to engines he's actually had apart.
Unless the SB recommends tearing down and wiping clean the engine parts, then some of the last oil will always remain within it. It cannot be removed.
Sounds like a bad engine looking for an excuse as to the reason that it's so or maybe recommended drain intervals extended a few thousand kilometers too far.
 
Are we trying to squeeze blood from a Turnip, like a bypass filters,,, who has worn out a properly maintained engine?
 
Status
Not open for further replies.
Back
Top