At some point my oil cap came off my car and was lying broken in the streets. No idea how long I had been driving the car without the cap and I hope I didn't get any water in there (It has been raining lately). Should I change the oil just in case? I lost about half a quart of oil from the filler hole.

If there is water in your oil you could see it. The oil turns tan and has the consistency of yogurt. If you see any evidence of that, change the oil.

[This message has been edited by Gall757 (edited 03-29-2014).]

Here's a real simple test to see if you have water (or coolant) in your oil.

Start the engine and let it come up to temp. Pull the dipstick out and let the oil on the dipstick drip onto the exhaust manifold close to the engine head (where it will be very hot). If you hear any sizzling then you likely have water in the oil. You're listening for the sound water would make when it hits a surface that is hot enough to boil it immediately. If there is not any water in the oil you will not hear anything - the oil will burn silently.

i was trying to heat up a stuck oil pan bolt and thought i heard a boiling sound? the oil looks light brown when i pull the dip stick,, i never drove the car so don't know much about it, could there be water in the oil? car not moved in 5 years

[This message has been edited by nickbrown (edited 03-29-2014).]

Condensation in the oil after years of sitting is a no brainer. Change the oil before starting this engine or you will have internal problems soon.

quote Originally posted by nickbrown: i was trying to heat up a stuck oil pan bolt and thought i heard a boiling sound? the oil looks light brown when i pull the dip stick,, i never drove the car so don't know much about it, could there be water in the oil? car not moved in 5 years

I dont recommend using anything to heat up an oil pan bolt, oil can burn and it would be hard to put out an oil fire.

Change the oil, it's cheap and it cannot possibly Hurt.