Doing things because that's how you were taught
Discussion
I was changing the oil on one of my cars over the weekend. I was about to turn the engine on to warm it up first, when I stopped and thought "why am I doing this?". Well, I was taught that you get the oil warm before you drain it.
In winter, I suppose warm oil runs out more quickly than cold oil. Especially so with old types of oil. But I'm sure I was taught "running the engine will help push the oil everywhere and clean out the dirt". Well, what will it pick up that it didn't get on the previous run? Isn't the oil in the sump now just as dirty as it would be if I run the engine for another 10 minutes?
I drained the oil, room temperature, just the dirt that was already in it. Only difference was the removal of burn risks, and that there might have been a few teaspoons more oil drained out because it wasn't splashed around inside the engine first.
So, is there another reason I should have run the engine first?
Have you got any spannering habits that make no sense in the modern world?
In winter, I suppose warm oil runs out more quickly than cold oil. Especially so with old types of oil. But I'm sure I was taught "running the engine will help push the oil everywhere and clean out the dirt". Well, what will it pick up that it didn't get on the previous run? Isn't the oil in the sump now just as dirty as it would be if I run the engine for another 10 minutes?
I drained the oil, room temperature, just the dirt that was already in it. Only difference was the removal of burn risks, and that there might have been a few teaspoons more oil drained out because it wasn't splashed around inside the engine first.
So, is there another reason I should have run the engine first?
Have you got any spannering habits that make no sense in the modern world?
ian332isport said:
Historically, it was to make the relatively thick oil a bit thinner, so you get more out. These days, modern oil isn t much thicker than water, so not such an issue.
I'd agree with this. Hotter oil just flows a bit better so there's less of a film on the bottom of the sump when you drain it. I usually don't get the oil boiling hot, just warmed (unless doing my air-cooled car which requires the oil to be piping hot and holds about 12L of oil!). I've never thought about the 'dirt' at least with regards to oil temperature when doing an oil change. donkmeister said:
I was changing the oil on one of my cars over the weekend. I was about to turn the engine on to warm it up first, when I stopped and thought "why am I doing this?". Well, I was taught that you get the oil warm before you drain it.
In winter, I suppose warm oil runs out more quickly than cold oil. Especially so with old types of oil. But I'm sure I was taught "running the engine will help push the oil everywhere and clean out the dirt". Well, what will it pick up that it didn't get on the previous run? Isn't the oil in the sump now just as dirty as it would be if I run the engine for another 10 minutes?
I drained the oil, room temperature, just the dirt that was already in it. Only difference was the removal of burn risks, and that there might have been a few teaspoons more oil drained out because it wasn't splashed around inside the engine first.
So, is there another reason I should have run the engine first?
Have you got any spannering habits that make no sense in the modern world?
Running the engine wouldn't make any difference to the contaminants. They don't hide elsewhere when the engine is cold.In winter, I suppose warm oil runs out more quickly than cold oil. Especially so with old types of oil. But I'm sure I was taught "running the engine will help push the oil everywhere and clean out the dirt". Well, what will it pick up that it didn't get on the previous run? Isn't the oil in the sump now just as dirty as it would be if I run the engine for another 10 minutes?
I drained the oil, room temperature, just the dirt that was already in it. Only difference was the removal of burn risks, and that there might have been a few teaspoons more oil drained out because it wasn't splashed around inside the engine first.
So, is there another reason I should have run the engine first?
Have you got any spannering habits that make no sense in the modern world?
As others have said it made a difference to the viscosity in older cars, but these days there's very little difference IMO. Engines and engine oils have moved on quite a bit.
I certainly clean the mating surfaces. I hadn't considered just how corroded they can be until I saw someone demonstrating a quick buff up with a roloc disc.
I've got two drill attached things for this now; one has a central hole with wire brushes so you can do round the studs, the other is a flat face disc so you can do the flat parts of the mating surfaces.
Obviously you don't want to go mad and end up with wobbly faces, but just enough to scrape the crud off. I always douse it with water to keep the dust down, then a final wash with brake cleaner.
Re copper slip, a chap I worked with simply used to remove every wheel a couple of times a year for a clean, and he never had one seized on. Not suggesting we all do that but can't argue with results
I've got two drill attached things for this now; one has a central hole with wire brushes so you can do round the studs, the other is a flat face disc so you can do the flat parts of the mating surfaces.
Obviously you don't want to go mad and end up with wobbly faces, but just enough to scrape the crud off. I always douse it with water to keep the dust down, then a final wash with brake cleaner.
Re copper slip, a chap I worked with simply used to remove every wheel a couple of times a year for a clean, and he never had one seized on. Not suggesting we all do that but can't argue with results
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