Used Motor Oil Promotes Rust

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JHZR2

JHZR2

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Anyone else hear this?

Noticed it mentioned a few times when doing sme other reading on rust protection.

As if the additives, the acids in it, or something else may cause additional issues.

It doesnt really make sense to me, but apparently it has been mentioned in older VW service manuals and elsewhere...

Anyone else hear this and understand why it may be the case?
 
Promotes rust where? In the engine?

I would guess (this coming from a layman with little auto knowledge and even less motor oil lubrication knowledge) would be acid buildup in the oil stripping protective coatings created by the additives from ferrous parts, thereby promoting rust.
 
That's not true at all. not even a bit. I have multiple vehicles with hundreds of thousands of miles on most of them and they were all sprayed with waste motor oil for years, no rust in northern NY.

now I like fluid film, works just as good and is easier and cleaner.
 
Last edited:
Originally Posted By: NMBurb02
Promotes rust where? In the engine?



No exterior... (detail and wax section).

Apparently it was part of VW service manuals back in the day. Trying to get that cited.

Doesn't make much sense to me...

Also saw one place that linseed oil, and another that bar and chain oils are good...
 
Originally Posted By: JHZR2
No exterior... (detail and wax section).

Oops.
blush.gif
 
Ok, wait.... Maybe I'm missing something. What use is old used oil? Other than spraying it around your house foundation as a pesticide?

I'm down south and originally from NY... but moved when I was very young. Can someone explain?
 
Right.

As good a use as any I guess. Though Id likely buy (I already own some) rust inhibiting oil purpose-made.

It was just an interesting commentary really.
 
Well the used oil contains Iron and other metal particles after being used in the engine. Which could react with the metal that its being applied to. Most if not all of the additives are used up. So now you have oil loaded with contaminants that can react with the metal.
 
Yeah, but the mass of these contaminants is tiny compared to the oil mass, and assuming the TBN isnt depleted, the oil isnt really acidic.

I wouldnt do it just because of the carcinogenity of oil...

Id use Krown/Carwell or CorrosionX.

Just was an interesting thing I read... Apparently there was a published test done ~30 years ago that compared various routes.
 
For what it is worth, I sprayed our work plow truck with old, but never used 10 weight non detergent oil from a spray bottle along the entire frame and underbody. It sat in a heated garage for 2 days before being used for plowing again. The next spring there was nothing....I mean nothing left to say that oil was ever there except for a still rusty frame. That proved to me whatever Krown (Carwell here) rustproofing uses it totally different from just plain oil. I've never used dirty engine oil before, but I know clean oil just gets washed away quickly. Same for WD40. Looks good at first, but looks rustier a month later? I have no idea why.
 
Spraying waste oil on vehicles to prevent rust is bad for the environment. You minds well also pour it on dirt roads to control the dust like was done many years ago. The oil will get washed off into streams and waterways. Products designed for this should be used (Fluid Fil or CarWell.)

Just think if everyone who went to Jiffy Lube and after they drained the oil they sprayed it on the undercarriage. What a disaster that would be.
 
I knew an older gentleman many years ago that would spray Used Motor Oil in a long wand garden srpayer and spray his old Ford F Series Truck each year prior to winter and he let the truck drip inside the barn. It kept his truck from rusting during the very salty winter we experience hear in Western NY.

This was also when Ford had very bad rust conditions in their metal/paint prep in the early 70's and the used oils came from everything carburated. I think that this gentlemans paint would still experience that dreaded peeling problem that Ford had but, the truck wasn't turning into a cancer case from rust.

With todays technology, I would like to see better rust protection "STILL" on the whole vehicle including the whole undercarrage, fuel, brake, p/s lines and fuel tanks especially here in Western NY where the HW Dept's use more salt than just about anywhere in the country.

For what vehicles cost today and the resale values that they are holding, the rust protection isn't where it needs to be IMHO!
 
Last edited:
Originally Posted By: Char Baby
I knew an older gentleman many years ago that would spray Used Motor Oil in a long wand garden srpayer and spray his old Ford F Series Truck each year prior to winter and he let the truck drip inside the barn. It kept his truck from rusting during the very salty winter we experience hear in Western NY.

This was also when Ford had very bad rust conditions in their metal/paint prep in the early 70's and the used oils came from everything carburated. I think that this gentlemans paint would still experience that dreaded peeling problem that Ford had but, the truck wasn't turning into a cancer case from rust.

With todays technology, I would like to see better rust protection "STILL" on the whole vehicle including the whole undercarrage, fuel, brake, p/s lines and fuel tanks especially here in Western NY where the HW Dept's use more salt than just about anywhere in the country.

For what vehicles cost today and the resale values that they are holding, the rust protection isn't where it needs to be IMHO!


My fil still does that on the farm. It's in his barn. Dirt floor. No weeds grow in there,not much for rodents either.
I don't know how but he also uses used oil in his furnace. It's an oil furnace. I've never heard of it until he told me about his. He actually gets all my used oil.
 
Originally Posted By: BituminousCoal
That's not true at all. not even a bit. I have multiple vehicles with hundreds of thousands of miles on most of them and they were all sprayed with waste motor oil for years, no rust in northern NY.

now I like fluid film, works just as good and is easier and cleaner.

Fluid film is great stuff. Works well.
 
I spray used motor oil on my Focus and my Cherokee. The cherokee is still in pretty good shape and the Focus hasn't started to rust (yet)

Originally Posted By: Char Baby

This was also when Ford had very bad rust conditions in their metal/paint prep in the early 70's and the used oils came from everything carburated.


Ford still has rust problems.
 
Originally Posted By: Donald
Spraying waste oil on vehicles to prevent rust is bad for the environment. You minds well also pour it on dirt roads to control the dust like was done many years ago. The oil will get washed off into streams and waterway.

Just think if everyone who went to Jiffy Lube and after they drained the oil they sprayed it on the undercarriage. What a disaster that would be.


Ya I know but everyone doesn't. So the problem doesn't exist.

Where did the oil come from to begin with, the enviroment?
 
Originally Posted By: JHZR2
Originally Posted By: NMBurb02
Promotes rust where? In the engine?



No exterior... (detail and wax section).

Apparently it was part of VW service manuals back in the day.



What do you mean "apparently"? Why would it be in old manuals and not in newer ones?
 
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