Q: My car blows white smoke out of the tailpipe.

Whenever I'm stopped at a downhill and I reverse, I see a big puff of smoke coming from my tailpipe, it's very noticeable and goes away once I start driving forward. Sometimes when I'm at a stop and I accelerate, I see the puff of smoke again but isn't as big as when I go in reverse. I bought the car about a month ago and all it has is an exhaust, no other modification to it. I got a compression test done before purchasing but it was only a dry compression test, it read around 168 psi in all four cylinders with no huge difference between each. I was going to take a small trip so I checked the oil and water only to find that the oil had was very low after one month of owning the vehicle (had tune up pre-purchase.I put 1000 miles on it, got the car at 106,000) I added oil and it hasn't gone down over the past week. The coolant has not gone down at all and has stayed at one level. Oil is not milky and coolant hasn't gone down so ruled out head gasket. Maybe bad oil rings?
My car has a manual transmission.