Toyota 3ur-fe 5.7l v8 engine camshaft tower seal is prone to premature failure, which leads to engine oil leaking on the hot exhaust manifold, which could cause potential fire/flash hazard. more details (including photos) could be found in the recall petition at: https://www.change.org/p/toyota-motor-company-get-toyota-to-recall-cam-shaft-tower-leakage-problem-on-5-7l-v8-3ur-fe-engine?source_location=topic_page
Unburnt fuel is entering the exhaust system and combusting when it comes in contact with the catalytic convertors. this happens almost every time it is driven. this has been happening from the day we bought it. took the truck to dick hannah toyota in longveiw wa. they had never heard of this. the talked to the factory but nobody has a solution. the dealer tried a similar truck and got the same results. they talked to the toyota field rep. and he stated he could make this happen to his tundra when ever he wanted? this has happened while incruise control also.