I was just wondering how bad is it to engine brake during high speeds? Sometimes on highways traffic jams just come out of nowhere, and when you're traveling at 70MPH and all of a sudden the cars in front of you are coming to a dead stop you gotta to do what you gotta do in order to avoid a collision. I hit the OD button (to activate OD light) and put the car in neutral and the car stops firmly.

I don't do it too often, only in case of an emergency. I was just wondering what could come of it if it was used casually.

 

Nothing will come of it casually but if you were to constantly use it, there will be slightly more wear and tear. The engine and the tranny are not meant to slow the vehicle, except when you are on a downhill and are slowing down your descent and that is only casual usage unless you live in a hill infested part of the country.