[RozesofSharon]

So, now we know just to turn the key. Not to put the pedal to the metal... but should we change the oil because we did do it when we didn't know better?
Could have we did some kind of damage?

And... if the weather threatens to get that cold again, what can we do to try to prevent all this?

We don't have access to a garage.

Does Isophyl help?