I am very late, but I noticed some people breaking a rule last week (at fuji), and would just like to point this rule out, so those people can see without naming names, or addressing them directly
Note the highlighted bit in red
Defending
You’re defending your position, so chances are the guy behind you is quicker than you right now. But that’s no problem, because you have the advantage of choosing your line through every corner. But that doesn’t mean you can go wide into a corner and then slam the door shut by swerving back in 3 inches in-front of the car behind you. Make sure you know where the guy behind you is, if you know he’s going for an overtake then remember to leave room for him either on the outside or inside of the corner.
When the car behind you is in your slipstream, it is considered incredibly rude and unsportsmanlike to swerve all over the track to break the slipstream.
In addition, this rule is relevant in cases of blue flag situations (lapped cars)
• Lapped cars may not attempt re-overtake +1 lap cars until the lap after the current lap is over, all lapped cars must yield as soon as possible in a safe way. Pull off the racing line and apply the brakes momentarily.
Although the rule states that a lapped car can pass/use slipstream to get ahead of the lapping car in the next lap, I think most of us would recommend against it unless you know for an absolute fact that you are faster than them and they will not catch up to you once you pass them.
Most likely, if you're getting lapped, you're not as fast as the driver that's lapping you, and although using slipstream may help you at the time, it's not worth the risk of having an incident with that car, when they are passing you back
You're not racing a car that's a lap ahead. If you pass them and they catch up to you, you're then obligated to let them by when you're in front of them, so what's the point right?
Basically, just use some common sense, and don't assume the car a lap ahead of you is Cal Nawton Jr telling you "slingshot engaged" . Just because the slipstream is there for the taking doesn't mean you should take it. I know as well as anyone it's tempting, but it's not worth getting on the nerves of your fellow racers
Thanks