How detrimental is it to...

PapoZalsa

I was reading something about this this morning. What I can remember about the article that I read was that the modern engines are not like the old ones that need it to warm up for a few minutes to get the oil circulating and up to specific temp.

The modern engines work diferently so in a few seconds all the engine components will be well lubricated and ready to go.

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Red__Zed

The need to warm the engine up stems primarily from the desire to get the motor oil up to temp. If you wail on your car while it's cold, you are essentially running 5 weight oil in the engine...

ImportConvert

No, you're running something thick as syrup and it doesn't lubricate as well, or pump NEARLY as well. In other words, you have more pressure at the pump and less up top and over the bearings.

No, you won't blow your car up the first time, but it's not a good habit at all. That is why many high-end cars have tach's that adapt to the running temp like the M series, etc.

Red__Zed

What exactly are you disagreeing with in my post?

ImportConvert

I am disagreeing with the way you say "running the engine with 5-weight oil".

That is deceptive in that the oil is very thick when cold. cSt of most "X"-30 weight oils is around 60 when cold. When you heat them up, the cSt drops to around 9-11.

The way you presented it makes it sound like oil is thinner when its cold.

Red__Zed

I apologize if my comment caused confusion. I meant it behaves as a cold 5W oil, giving it a (slightly) higher viscosity. I guess I should have fleshed that comment out more.


Not sure where you get the 60cSt number. It's usually below 20, at least for a 5W oil.

Viscosity Charts

ChrisSlicks

Because it isn't an SAE-5 oil, it is an oil blend. A 5W30 isn't going to perform the same as a SAE-5 or an SAE-30, most of the time it is somewhere in between. It's properties are such that it can pass the minimum test for SAE-30, however there actually isn't any standardized test for Winter weight and most oils certainly wouldn't pass the test of SAE-5.

The viscosity numbers quoted (60 cSt @ 100F) is an average from actual manufacturer test data. On a cold start on a cold day it will be slightly higher, probably around 80-90.

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