White Smoke from exhaust

White smoke is from water burning in the combustion chamber, which is normally from a leaking headgasket. Bad rings will allow oil into the combustion chamber, and be a bluish gray color. If the coolant level has been dropping and/or the engine overheating, then it's likely the former.

First of all, did the noticeable white smoke start about the time of colder weather. If it did, it could be totally normal as when any engine is first started, a lot of condensation is formed inside the exhaust system and will appear as whit smoke or steam until the exhaust system heats up enough to eliminate this moisture. You may also see some water, (clear in color) leaking out of the muffler until after the engine completely warms up. Be aware though that the four cylinder engines is some RAV4's and Highlanders do have a head bolt thread concern is a very small amount of their engines, and will be associated with coolant loss. (Keep have to add coolant to the reservoir) If your not overheating and running out of coolant you are most likely just fine and when warmer weather appears the steam will not be noticeable. As far as (O-Rings)?? I'm not sure what this person is referring to.