Radiator cockpit

I do not recommend using the petcock ever. They are made of plastic, and have an o-ring on the stem that seals against a flat sealing surface that is part of the radiator tank. There were way too many problems not too many years ago where that sealing surface would crack when the petcock was tightened, then you would have a leak. Coolant would drip a drop about every five seconds. The only fix for that was to replace the radiator. Because of that history, very few mechanics ever use the petcock. Instead, we just remove one end of the lower radiator hose. The coolant will come gushing out faster, but overall, it will not be a whole lot messier.

Most of this style of petcock must be rotated counter-clockwise a quarter turn, then they must be pulled straight out to open them. Pulling them out often requires a pliers to grab onto them, and space is usually too tight to do that on most vehicles. Those petcocks are made of plastic too, and it is not unheard of for one to break. If the handle snaps off when the valve is part-way open, you will have no way to close it again to keep it sealed.