In the owners manual it says to perform scheduled maintenance after a certain number of miles or months, whichever comes first. My question is, why would you need to change the oil if the car isn't being used? If it's just not racking up the miles, it doesn't seem like it would need its oil changed. Is this just a way for dealerships to get you in for service on a more regular basis?

 

no oil degrades with time and looses its properties

 

because everything collects contaminants if it's not removed regularly...it will help protect you from a major breakdown due to lack of maintenance and it will extend the life of major components in your vehicle....

 

Only if the engine, diff or trans HAS NEVER been run could you let it sit without there being problems. It's not the fluid that breaks down, it's the by-products of its use that cause problems. The by-products of combustion will cause pitting and scarring of a bearing surface if allowed to settle for a long period of time. Seals and gaskets will shrink and dry if not regularly oiled by normal operation also. Sorry to disappoint the paranoid, it is not another secret plot of the dealers to take your money.

 

I am aware that letting a car sit is harder on it then use, and that shorter trips in the city are harder than long trips on the highway. My question is more how changing the oil would help prevent those problems. What you said addresses how the engine suffers if the car isn't used. But in my situation, I use the car everyday, but only for short trips, so the mileage just doesn't pile up. I'm wondering how changing the oil helps anything.

 

Just leave the oil in there then, don't ever change it.

 

Why spend 50 bucks changing your oil every 3 months. What a waste of money on your 30000 dollar investment.

 

Well, if the oil hasn't deteriorated, why change it? It's not the money, it's called intellectual curiosity (I know, it's probably a foreign concept to you).

 

It's an either/or thing. Every 3 months OR 3k whichever comes first. Oil starts to degrade the minute you start using it. They aren't really worried about the oil as much as the potential wear on the affected components. The longer the oil stays in use the more combustion gases get in the oil, the more of those product means less oil. The older the oil is the more likely it is to get burned off because it has been diluted. That is why old oil smells like gas and exhaust.

 

/deleted/

 

My father-in-law used to drive everywhere he went. His workplace was four blocks from home. He drove. In the winter the oil level in the engine of his car would go up not down until it was way over full. This was gasoline accumulating in the oil because the engine never got hot enough to evaporate it off.

The point is there are owners who use their vehicles like this and if you don't include a time period for oil changes they will damage their machines.