Manufacturers of motor oil for car engines have found through research

Question

Manufacturers of motor oil for car engines have found through research that motor oil slowly loses lubrication effectiveness after the car is driven for certain distances. On average, the motor oil is only fifty percent as effective after 3,000 miles of driving as it is the first day it is put into the car. For that reason, people should replace their motor oil every 3,000 miles.

Which of the following, if true, would most weaken the conclusion above?

(A) The research indicates that the oil loses effectiveness because it becomes dirty.

(B) The researchers found that there was not a significant difference in the effectiveness of motor oil in cars that reached 3,000 miles quickly versus those that took a long time to reach 3,000 miles.

(C) The researchers found that cars with motor oil at fifty percent effectiveness showed no more signs of damage or wear than those with fresh motor oil.

(D) The researchers were paid by the manufacturers of motor oil, who have a vested interest in selling more motor oil.

(E) Both synthetic and non-synthetic motor oils experience similar losses in motor oil effectiveness after 3,000 miles of driving.

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BradfordGrady · Answer

To weaken the conclusion that people should replace their motor oil every 3,000 miles, we need to find a statement that challenges the necessity of this replacement based on the effectiveness of motor oil.
Let's evaluate the options:
(A) The research indicates that the oil loses effectiveness because it becomes dirty.
 
 This supports the idea of changing oil but doesn't weaken the conclusion.  
(B) The researchers found that there was not a significant difference in the effectiveness of motor oil in cars that reached 3,000 miles quickly versus those that took a long time to reach 3,000 miles.
 
 This doesn't directly address the effectiveness threshold for changing oil.  
(C) The researchers found that cars with motor oil at fifty percent effectiveness showed no more signs of damage or wear than those with fresh motor oil.
 
 This directly undermines the conclusion by suggesting that even at fifty percent effectiveness, the oil does not harm the engine, indicating that changing oil may not be necessary every 3,000 miles.  
(D) The researchers were paid by the manufacturers of motor oil, who have a vested interest in selling more motor oil.
 
 This raises questions about the integrity of the research but does not directly address the effectiveness of oil or the necessity of changing it.  
(E) Both synthetic and non-synthetic motor oils experience similar losses in motor oil effectiveness after 3,000 miles of driving.
 
 This reinforces the idea that oil should be changed but does not weaken the conclusion.

The option that most weakens the conclusion that people should replace their motor oil every 3,000 miles is:  geometry dash meltdown 
 (C) The researchers found that cars with motor oil at fifty percent effectiveness showed no more signs of damage or wear than those with fresh motor oil.

Whoisdmx15 · Answer

(A) The research indicates that the oil loses effectiveness because it becomes dirty . Eliminated As the conclusion is about changing motor oil, and not about the causes of loss in effectiveness, hence can be eliminated. ( Overthinkers like me would go into the spiral of, if it only the question of dirt in motor oil, it can very well be accumulated in less than or far more than 3000 Kms, and hence this should undermine the conclusion. Please don't go down this rabbit hole

) (B) The researchers found that there was not a significant difference in the effectiveness of motor oil in cars that reached 3,000 miles quickly versus those that took a long time to reach 3,000 miles . Eliminated This instead of weakening the conclusion strengthens it, that loss in effectiveness is a function of distance traveled and not time elapsed. (C) The researchers found that cars with motor oil at fifty percent effectiveness showed no more signs of damage or wear than those with fresh motor oil . Suitable This actually poses the biggest challenge, as even at 50% effectiveness, motor oil sufficiently prevents wear and tear, hence we should only change motor oil only till it becomes significantly ineffective in preventing wear. (D) The researchers were paid by the manufacturers of motor oil, who have a vested interest in selling more motor oi l. Eliminated This seems lucrative, but a stronger weakening statement is available based on facts. (E) B oth synthetic and non-synthetic motor oils experience similar losses in motor oil effectiveness after 3,000 miles of drivin g. Eliminated This again strengthens the conclusion that loss in effectiveness is a function of distance and not type.

bhargavhhhhhhhh · Answer

Given:
- Motor oil loses 50% of its effectiveness after 3,000 miles.
- Conclusion: People should replace motor oil every 3,000 miles.

Step 1: Look for a statement that weakens the conclusion.

(A) The oil loses effectiveness because it becomes dirty. 
- This doesn't weaken the conclusion as dirty oil could still need replacement after 3,000 miles.

(B) No significant difference in oil effectiveness between cars that reach 3,000 miles quickly vs slowly. 
- This doesn't weaken the conclusion because it still supports replacing oil after 3,000 miles.

(C) Cars with motor oil at 50% effectiveness show no more damage or wear than those with fresh oil. 
- This weakens the conclusion because it suggests that oil effectiveness doesn't correlate with engine damage, so replacing oil at 3,000 miles may not be necessary.

(D) The researchers were paid by motor oil manufacturers, who have a vested interest in selling more oil. 
- This is a potential bias, but it doesn't directly weaken the conclusion based on the findings.

(E) Both synthetic and non-synthetic motor oils experience similar losses in effectiveness after 3,000 miles. 
- This doesn't weaken the conclusion as it still suggests 3,000 miles is the point where oil effectiveness drops.

Answer: C. The researchers found that cars with motor oil at fifty percent effectiveness showed no more signs of damage or wear than those with fresh motor oil.

Nikkz99 · Answer

For  that  reason,  people should replace their motor oil every 3,000 miles.

reason -> vehicle loses lubrication effectiveness after some distance.
conclusion -> motor oil should be replaced every 3k miles.

We must now  weaken  the above conclusion now.

From the above 5 options, A,B & E doesn't even weaken the conclusion a bit.

(C) The researchers found that cars with motor oil at fifty percent effectiveness showed no more signs of damage or wear than those with fresh motor oil. -> Here we are stating that 2 kinds of oil such that existing oil have same impact as the new oil.

(D) The researchers were paid by the manufacturers of motor oil, who have a vested interest in selling more motor oil. -> states a bias opinion but option C is more appropriate which directly attacks the conclusion part and weakens the above statement.

So, Option C is the right choice.

Bunuel · Answer

Official Explanation

Answer C

In this argument, the conclusion is that people should change their motor oil every 3,000 miles. The conclusion is based on the fact that motor oil loses half of its effectiveness after being driven that distance. The central assumption here is that the loss of effectiveness is indeed a valid reason for changing the motor oil. Choice (C) challenges this assumption by saying that cars with motor oil at fifty percent effectiveness do not have any ill effects. Thus,  choice (C) is the correct answer.

Choices (A), (B), and (E) are all out of scope. The fact that oil loses effectiveness because it becomes dirty does not weaken the conclusion. It also does not matter that cars that reach 3,000 miles at different rates experience similar declines in motor oil effectiveness; it also does not matter that the same is true of cars with different types of motor oil.

Choice (D) may be tempting, but is ultimately irrelevant. We may want to gravitate to a choice like (D) that questions the motives for the research, however we never want to challenge the evidence itself in a weaken question – only the central assumption. Even though the research was conducted under the supervision of motor oil companies, this does not alone weaken the conclusion that motor oil should be changed every 3,000 miles.

Maitreyeejoshi · Answer

Really helps, Thanks! However does not suggest that it gets dirty so might just need to clean it and not replace

celialem · Answer

I was tempted with choice D but then I remembered that the motives of the research don't really matter. The conclusion is that people "should" change their motor oil every 3000 miles, and choice C provides an explanation that actually there is no need as there is no damage on the car whether it's oil that's 50% less effective or newly changed oil. So, essentially, people don't need to change the oil every 3000 miles, hence weakening the conclusion.

Manufacturers of motor oil for car engines have found through research

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Manufacturers of motor oil for car engines have found through research

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