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Oil change, DIY vs shop (lemmy.world)
submitted 1 week ago by to c/dadsplain@lemmy.ca
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If you read any manual on changing your oil, it's going to tell you to let that thing drip for 15 to 30 minutes to clear out as much of the old oil as possible. Meanwhile, your average oil change place is advertising that they will have you in and out of there in 15 minutes from start to finish. Which means there's no way they're letting it drip the minimum of 15 minutes.

The soil change was so overdue. There is a difference between the service interval and abuse interval of oil. I definitely got into the abuse range on this occasion. I just didn't have the money for the oil and the filter.

And while you're taking care of your own oil change. Make sure to check your brake fluid engine coolant and washer fluid and top them off as necessary.

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[–] 8 points 6 days ago* (3 children)

The oil change was so overdue. There is a difference between the service interval and abuse interval of oil.

For others reading about why changing oil is important: Modern engines use oil for lubrication, yes, but the oil system is also designed as the "sewer" where all the dirt and crap get dumped. Because the oil is flowing through the system and something that is changed a regular interval, it makes a convenient single-item maintenance to keep a whole bunch of bad stuff out of the engine. Imagine every time you have to go to the bathroom you had to store it inside your house. You would use up any container that seals first, then you'd be forced to use open containers, and not only the smell but the danger of diseases would be present. You'd keep those containers emptied outside as often as possible! When you don't change your oil for long periods of time, you're keeping your raw sewage of your engine right next to the engines kitchen and work space.

In short: The primary reason for changing the oil isn't that the oil stops lubricating, its that, over time, it carries all the bad stuff suspended in it. The way to keep the engine clean is to change the oil at regular intervals.

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  • [–] 5 points 6 days ago

    The oil does in fact stop lubricating well too. Shear is a thing and the additive packages stop doing their magic over time too.

    Still, unless you live in the desert, the body of most cars will rust through long before you spin a bearing and those are the parts that are most affected by lubrication. Unless you completely neglect oil changes of course. I'm on only 420k km and already the 20 year old rocker panels are perforated on my Audi. Engine probably has another 200-300k km in it, but the car will be unsafe to drive long before that.

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  • [–] 0 points 6 days ago (1 child)

    Oil filters are a thing, eh.

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  • [–] 3 points 6 days ago*

    Sure, filters extend the life of oil, but they do that by using a porous filter media. The larger particulates get stuck in the filter media, and the cleaner oil exits the filter...until all the microscopic holes get filled with particulate matter. Once the filter media is clogged, one of two things happens:

    • on cheap and horrible filters, oil goes into the filter...and never comes out. The engine runs dry, heat increases, and you spin a crankshaft bearing or blow a head gasket from the heat generated by increased friction. Engine dead.
    • on a good filter, the increased oil pressure from the clogged media forces open a bypass valve in the filter so oil (dirty unfiltered oil) goes straight through back into the engine. The concept being "dirty oil is better than no oil at all". However this means that the filter is now completely bypassed and the engine oil will continue to accumulate dirt and matter eventually clogging fine oil galleries and causing localized engine starvation of oil, spun bearings, increased heat, etc. Eventually, dead engine.

    Oil filters aren't an infinite life extension for oil. They help certainly, but this help is built into the maintenance schedule for changing your oil. Unless specifically noted by your manufacturer don't assume you can change just the filter and your old oil is fine.

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