Walmart Oil Change?

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The weather was bad in the midwest and my daughter needed an oil change this week in her Honda CR-V, 2.4L.. She normally does it herself with M1 and a Fram Filter.

Below are pictures of the oil before and after the oil change (spill and fill). Yes, the oil and filter was changed. This is not a dig towards Walmart or any other oil change service. Similar results occur even with DIY service.

1. New Oil in a vile.
2. New oil sampled from sump after 15 miles.
3. Blot test of the new oil after 15 miles and a standard oil change.
4. Blot test of new oil from the sump, after a 99% flush after 20 miles in my car.

Blackstone Labs confirmed that in modern engines, up to 20% of oil may remain in an engine.

How much of the serviceability of the oil is reduced by mixing with the old oil?

What impact to the the longer term engine life due to the remaining old oil?

Can that remaining oil last another full OCI?

If not, I assume the oil will oxidize and causing sludge, varnish, and carbon build-up in the engine.



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Originally Posted by Talent_Keyhole

What impact to the the longer term engine life due to the remaining old oil? - I'm sure the engine will last all the way to the tranny giving out, despite remnants of oil changes past.

Can that remaining oil last another full OCI? - sure, it lasted 300 million years in the ground, what's another 6 months?
 
Originally Posted by Jetsfan421
That oil passes the blot test to me. Run it the whole oci with confidence.


Where can I find more information on acceptable blot test criteria?
 
Originally Posted by tundraotto
You need to worry about new things. Oil is fine.


No issues with the QS conventional new oil. How do you know the old oil is fine?
 
Originally Posted by OilUzer
Experts say tribofilm is good and not to worry ...


Are you talking about Tribofilms created by Extreme Pressure lubricants such as ZDDP? Please elaborate?
 
Originally Posted by Mad_Hatter
Originally Posted by Talent_Keyhole

What impact to the the longer term engine life due to the remaining old oil? - I'm sure the engine will last all the way to the tranny giving out, despite remnants of oil changes past.

Can that remaining oil last another full OCI? - sure, it lasted 300 million years in the ground, what's another 6 months?



My last two transmissions outlasted engines by two fold due to regular full fluid exchanges, instead of spill and fills.

Your second comment is typical and does not pertain to the question.

Assuming that removing the filter and pulling the drain plug removed 99% of the oil in an engine, would you buy a name brand oil that contained up to 20% used oil of unknown quality, cleanliness, and contains wear metals, and combustion by-products?
 
Originally Posted by Mad_Hatter
Originally Posted by Talent_Keyhole
Originally Posted by Jetsfan421
That oil passes the blot test to me. Run it the whole oci with confidence.


Where can I find more information on acceptable blot test criteria?

There's actually "special" paper i believe..

https://www.machinerylubrication.com/Read/499/blotter-spot-method


So far standard business card stock seems to work well. I was hoping the article would provide more information such as the "standard comparator" as mentioned.

Do you have access to this comparator?
 
Originally Posted by tundraotto
You need to worry about new things. Oil is fine.

+1
 
Originally Posted by Talent_Keyhole
Originally Posted by Mad_Hatter
Originally Posted by Talent_Keyhole
Originally Posted by Jetsfan421
That oil passes the blot test to me. Run it the whole oci with confidence.


Where can I find more information on acceptable blot test criteria?

There's actually "special" paper i believe..

https://www.machinerylubrication.com/Read/499/blotter-spot-method


So far standard business card stock seems to work well. I was hoping the article would provide more information such as the "standard comparator" as mentioned.

Do you have access to this comparator?

I do not but Google blotter spot test and you'll find more than you care to know. At one point I was going to get into this but meh, that idea/motivation was short lived. BITOG member "Zeng" has done this test himself. DM him for first hand deets'...
 
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Walmart now does vacuum up the diptstick tube only. So depending on the vehicle some are better suited for this than others. I tried my own vaccum oil out the dipstick tube on my old 93 Honda Civic and could only get 1 qt out. Theirs is probably better than that but you also have to consider who is doing it and are they in a hurry to get to break or off work or finish up so they can sit. You just never know unless you can watch them.
 
My dodge 318's dipstick is pretty narrow. Widest tubing I could fit down it was aquarium bubbler tubing. I set up a siphon, with cold oil I drained a quart per day!

A vacuum only has 15 PSI behind it. I don't see that working too much better.

But, hey, I'm not Walmart. Their logistics are pretty good most of the time.
 
Originally Posted by spk2000
Walmart now does vacuum up the diptstick tube only.


LOL they got tired of replacing drain plugs they lost. Yes one time on vacation WM changed my oil it took them over two hours. When we got back from the Gulf a I changed my oil again I had some real funky drain plug it sure wasn't my stock Duramax plug. Made in China.
 
Why include "Walmart" in the subject or even refer to it ? Everything you mention pertains to all oil changes, even "perfect" ones that people DIY.

That said, you're seriously overthinking this. Tell you daughter everything's fine and to change it when the OLM tells her to. I presume it goes 5000-8000 miles typically ?
 
Originally Posted by hallstevenson
Why include "Walmart" in the subject or even refer to it ? Everything you mention pertains to all oil changes, even "perfect" ones that people DIY.

That said, you're seriously overthinking this. Tell you daughter everything's fine and to change it when the OLM tells her to. I presume it goes 5000-8000 miles typically ?


Or the no brainer is change you OCI's to April and October and it just is no longer a issue unless you live in an ice zone.
 
Use a garage ? Even an unheated one will be warmer than directly outside. Our garage maintains 50-55º F if the outside temperature is in the 30s. Or, waiting a week or even a thousand miles for a bit warmer weather isn't going to make a difference. No car needs the oil changed right now.
 
Originally Posted by hallstevenson
That said, you're seriously overthinking this. Tell you daughter everything's fine and to change it when the OLM tells her to. I presume it goes 5000-8000 miles typically ?


Agree the oil will be fine. I'd recommend to check the oil level every two weeks or so. And top off if necessary of course.

I'm considering having WM TLE do the next oil change. I don't think they always use the extraction method for oil changes. Prob depends on the car, how busy they are, who's doing the oil change, etc. Plus you can easily stand in the vicinity and watch them. I've had pretty good luck there. Name brand oil and filter for $20. They check the oil level before doing the oil change service and notate it on a report.
 
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