Changing the Oil (the experts are wrong)

Mendel

Senior Member.
I like this as an example how it doesn't take a conspiracy theory to think "I know what I saw, the experts are wrong".

Please watch this short video, it's only 1:38 minutes.

Source: https://youtube.com/shorts/8uBFyVWuWsw

It's about someone who changes the oil in their differential, filling it up to the hole, and finds that the amount given in the manual is wrong. The video demonstrates this clearly.
Commenters pointed out that the method only works correctly when the car is level, but the car in the video is not.
The author admits that he raised a wheel up to get a better camera view, which tilted the car, raised the hole, and led to him overfilling the differential. The manual was correct, after all.
When you think you've found an error in well established knowledge, it's usually the best course of action to figure out what you got wrong.

This was a very shallow rabbit hole, and the video's author escaped easily.
But mentally, the attitude of taking "I've found something wrong" un-self-critically (or trusting people who have this attitude) is tempting, and should prompt everyone to triple-check the evidence and their understanding of it,
 
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When you think you've found an error in well established knowledge, it's usually the best course of action to figure out what you got wrong.
Given that I don't know of a "quart" such that two of them are 1.8L, my first guess was that the units on his bag-o-lube were different from the ones in the manuals (2 US quarts is 1.89L, so to 2 s.f. is "1.9L").. However, he is treating 3.8 pints as interchangeable with 2 quarts, so small disparities like that wouldn't be relevant.

However, I still think that he should fill it with the intended volume of liquid, not fill it till it spills out; as when he levels the car he'll have over-filled it. So he's double boobed, IMHO. However, I've never owned a car and all I know about differentials is the difference between Leibniz and Newton's notation.
 
However, I've never owned a car and all I know about differentials is the difference between Leibniz and Newton's notation.
What kind of lubricant do you use for these? Midnight oil? ;)

However, I still think that he should fill it with the intended volume of liquid, not fill it till it spills out
That is the intended amount—when the car is level.
 
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I like this as an example how it doesn't take a conspiracy theory to think "I know what I saw, the experts are wrong".

Except when the experts might actually be wrong. The thing about conspiracy theories, at least good ones, is there is some amount of truth involved. The guy in your video thought the experts at Ford where wrong in their recommendations for the diff oil, but what about the case of the General Motors experts possibly being wrong in their recommendations for engine oil?

In 2019 GM revamped its 6.2l small block V8 engine, calling it the L87. It employed various strategies to maximize fuel mileage, at least as much as one can in a 6.2l engine, including direct injection, progressive cylinder deactivation (running on anything between 2-8 cylinders as needed) and specking a thin 0W-20 oil. The lighter oil results in less friction, and supposedly results in slightly better gas mileage.

Then the new L87s started to fail:

External Quote:

The NHTSA Safety Recall Report shows GM's investigation included 28,102 complaints about the engine failure and 14,332 allegations of propulsion loss. GM also identified 12 potentially related crashes causing 12 injuries.
https://niada.com/dashboard/gm-issues-recall-for-600k-vehicles-with-6-2l-v8-engines/

One of GM's solutions was to change the oil specified for the engine (bold by me):

External Quote:

Amid an ongoing federal investigation into the 6.2-liter's potential catastrophic failure, the automaker is once again recommending that owners use a new kind of engine oil. The updated guidance is the second change for the L87, with the first intended to address a massive recall in April 2025.

That original recall, which followed an initial investigation by the National Highway Traffic Safety Administration (NHTSA), was upgraded to a full-scale recall of nearly 600,000 L87-equipped models. The fix, according to GM at the time, was to swap the V-8's original 0W-20 weight oil with a heavier Mobil 1 Supercar 0W-40 oil. According to a report by GM Authority, General Motors has now issued a new bulletin to dealers changing the recommended oil again, this time to Mobil 1 FS 0W-40.
https://www.caranddriver.com/news/a70288921/gm-oil-change-recommendation-changes/

The real culprit seems to be defective rod bearings and crankshafts that gets exacerbated by the thin oil, but even if one's engine is inspected and found to be defect free, the new oil specifications still apply (bold by me):

External Quote:

The recall was released in response to a supplier-related issue involving potential rod bearing contamination and crankshafts that may be out of spec. Per the recall procedure, every impacted vehicle must undergo an inspection, and from there, will be divided into one of two categories: those units that require a full engine replacement, and those that pass inspection but receive a revised oil spec and service procedure.

For owners whose L87 engines were inspected and did not need a full replacement, the oil change spec is the primary corrective action.
https://gmauthority.com/blog/2026/0...nreplaced-engine-with-0w-40-oil-doing-so-far/

So, the experts specified light weight 0W-20 oil originally which helped contribute to catastrophic engine failure and an eventual recall. The solution was to change the specifications to heavier 0W-40, but that might mean the advertised fuel mileage will be lower. In addition, one could get the idea GM is in full CYA mode with all of this (bold by me):

External Quote:

GM's 6.2L V-8 engine was first introduced in model year 2019 and is used in some of its top-selling models. The automaker has been aware of problems for some time. Shortly after its debut, customers complained of unusual noises, power loss and no-start conditions.

GM launched its first investigation into the problem in February 2022. Two additional investigations followed, which were closed in June 2023 and July 2024, respectively. Based on the available information GM had at the time, the root cause was not initially identified, according to the NHTSA recall report.

The fourth investigation, which was initiated by GM after the NHTSA opened its probe in January 2025, used an updated field data analysis to identify a suspect build period: March 1, 2021, to May 31, 2024. According to the recall report, 6.2L V-8 engines manufactured between these dates showed a higher rate of failure claims.
https://www.wardsauto.com/news/nhtsa-opens-investigation-gm-engine-failures-prior-recall/

So, after 3 internal investigations didn't really go anywhere, a 4th investigation, after the NHTSA started an external investigation, finally figured something out. The original 6.2l engines had a 5 year/50,00 mile warranty.

Is it conspiratorial thinking to suggest GM was stalling a bit, maybe trying to run out the 50,000 mile warranty on at least some of the vehicles with a number of inconclusive investigations? The final investigation reportedly had "updated field data", so one could argue that allowed them to arrive at a solution. And they did offer an extended warranty for inspected engines:

External Quote:
Engines that pass inspection will also receive a new special coverage program that extends warranty protection for 10 years or 150,000 miles from the vehicle's in-service date, whichever comes first.
https://gmauthority.com/blog/2025/0...od-engines-to-get-extended-warranty-coverage/

Where the experts wrong in recommending the 0W-20 oil? It's likely they knew nothing about the defective bearings and cranks, at least at first, and they were tasked with gaining every bit of mileage possible, so the decision may have made sense at the time. But, even engines that are deemed to not have the problematic defects are now to use the heavier 0W-40 oil. Are they saying the 0W-20 was too light and never should have been used in the first place? Are they saying the inspected engines should be defect free, but maybe not, so use the heavy oil just in case? Can one trust their different positions and changing recommendations? Is this a conspiracy to cover up what's really going on? ;)

I'm not a conspiracy minded person, but when I was looking to replace my 12 year old work truck last year with something more for a retired person, did I consider a GM? Not a chance.
 
Except when the experts might actually be wrong.
But note the course of events didn't start with "a guy in his home garage discovers a secret". The oil change issue is one that, if wrong, thousands of mechanics would have encountered before, because the DANA 50 is not new. The issue you're describing is so complex that the actual experts couldn't find anthing wrong with the first investigations, and the final investigation likely involved data from a great number of observations, not one anecdote of "my car broke, therefore GM designed it wrong". It involved other experts, too.

Note also that I didn't write "I've found something wrong" is always unjustified. It's just that the odds are against you (in a well-established circumstance), and you should act accordingly.

The radio just reported there's a wrong-way-driver on the interstate, but they got it wrong, there's hundreds of them!

The thing about conspiracy theories, at least good ones, is there is some amount of truth involved.
The "truth" in these is almost always ripped out of context and made to serve the overarching misinformation.

9/11? Truth: the towers collapsed.
Chemtrails? Truth: aircraft leave white clouds in the sky.
UFOs? People see things they can't explain.
Flat Earth? The Earth is almost flat.
Moon landing was faked? There was a moon landing.
Vaccines? They can have side effects.
Lizard people? .....
Elvis is alive? He was.
The 2020 election was stolen? Trump lost.

The "truth" in these conspiracy theories is the window dressing for the rabbit hole, nothing more.

It's true that this guy put more oil in his differential than he ought to have been able to.
It's his theory that explains it (the shop manual is wrong) that lacks truth.
Just because the starting point is true doesn't mean the rest of it is.
 
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