Originally Posted by
Alkemix
This is what i've HEARD. I don't know if technically this is 100% true:
Overnight, oil drips downwards into the pan and coverage on engine parts are minimal. During Idle, the oil pump does not exert enough pressure in order to redistribute the oil across all the engine parts. By running you car in idle, on cold starts, for extended periods of time, you're basically allowing your engine to be run with splashes of oil hitting it, rather than the gobs than can be pumped while in actual operation. It don't believe that revving in idle is also a good idea.
Wow if that were the case, engines would be seizing up left and right.
Engine's are NEVER designed where the oil pump can not exert enough pressure to distribute oil across the entire engine at idle. That would be stupid.
Unfortunately our Audi's don't have an oil pressure gauge. Have you ever had a car that has on oil pressure gauge? Did you ever pay attention to it? Most people don't pay attention to them, which is why they're rarely used.
An oil pressure gauge would prove all of this talk you guys are arguing about "not enough oil" is bunk. As soon as you turn a car on, the oil pressure rises to optimal pressure in less than 5 seconds. And that’s with out revving the idle. Generally, the oil pressure sensor is located near the top end of the engine. Obviously, over the life of the engine the pressure will gradually drop. But as long as the oil pump is operating, Oil will be distributed to the vital components quickly and consistently at idle.
Here’s the other thing: cold oil means higher oil pressure. I don’t care what you guys say or think; the oil pump is designed to pick up thick cold oil quickly in under 5 seconds. Again, if this were not the fact engines would be seizing up left and right. Those engineers in Germany are experts for a reason.
By the grace of God, I live in Texas so I don’t have to worry about changing my oil for the seasons. But some of you Yankees up north who think that idling a car in the cold is bad might want to consider what oil your running each winter.
This is completely a generic example, not Audi specific: 5w-30 takes 10 seconds to reach the valve train at 15 degrees Fahrenheit, compared to 20 seconds for 10w-30. Even worse, while 5w-30 is flowing freely in 40 seconds 10w-30 weight takes up to three minutes. Even better, consider switching to a synthetic oil, which will flow freely in 15 seconds at 15 degrees.
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