[trackbird]

As I was laying in my 40 degree garage today, changing the oil in my Camaro that had been parked since the night before, I remembered that most people seem to recommend changing oil when it is hot, so it drains better.

Now, my question is.

If oil is thin when cold (for start up protection) and gets thicker when it heats up, is it really a good idea to change it "hot". It did seem to take a while for the last of the oil to drain today, but I'm not sure that it should have. It was just an observation, early today, before I really woke up. So, if it is thin cold, and "thick" hot, shouldn't we change it cold? Or should we?

Just wondered what everyone else thought.....


(Nata, if this "takes off", kick it to engines or I will, it's a "general question" for now, isn't it?)

[DryStout]

Now, my question is.

If oil is thin when cold (for start up protection) and gets thicker when it heats up, is it really a good idea to change it "hot". It did seem to take a while for the last of the oil to drain today, but I'm not sure that it should have. It was just an observation, early today, before I really woke up. So, if it is thin cold, and "thick" hot, shouldn't we change it cold? Or should we?

Just wondered what everyone else thought.....

Change it hot. There will be more contaminates suspended in the oil.

The guidance you got about the behavior of the multiviscosity oils is correct [hot thin, cold thick still applies]. It is all spelled out in the SAE standard. The low # is for viscosity behavior at a low temp, and the high # is the viscosity behavior at a high temp.