My plugs are tight in there at 140k
Can I spray wd40 in there to loosen them up?

 

You can, and it won't hurt anything, but it's unlikely to penetrate very far. Remember, spark plugs have a really long thread. Just use a breaker bar and get them started, and you'll be all set.

 

Right. And if the 1,000 psi of the combustion cycle don’t vent out that thread and washer, a bit of water displacer isn’t going to get in. Use an extension/lever/bar like he said above. You can also run the engine and get the head a little hot. That expands it a bit and makes it easier.

 

Not sure but think I always heard to change when cold for aluminum and that plugs are seized when hot and plug can break off in removing. This has happened and motor has to be pulled and taken to a machine shop.

 

If you can't get the plug to crack loose when cold, then run the engine for a minute or 2, shut off, and try again.
This is not a "hot" engine but rather a warm one, but often it's enough to let the plugs be removed.
Make certain that you let the engine cool down fully before you fit the new plugs and always thread them in by hand to avoid cross-threading.