130 Lawn Tractor - White smoke after oil change

Hi guys. I'm a newbie here. Running into some issues with my 130 (from the 80's, not the newer L130) lawn tractor. Today was gonna be my first mow of the year, so I figured I'd change the oil, since it hadn't been done in quite a while. Followed the manual exactly. Cranked the mower and let it run for about 2 minutes to let the oil warm up. Then I drained the oil. Reinstalled the drain cap. Pulled out the dipstick, added 2 qts John Deere brand 10W-30 4-Cycle Engine oil, and reinstalled the dipstick. About 5 seconds after cranking it, I got white smoke. LOTS of white smoke. Let it run for about 10 seconds to see if it would clear up, only to get an even thicker cloud of white smoke.

All I did was change the oil. Mower ran just fine while it was warming up. Any ideas what this could be?

Thanks.