The process was excruciating, lasted for hours, and ultimately took approximately 10 years off of Luffy's life expectancy. He only survived the ordeal is because of his indomitable will to live. Both of these points and a few more are put forth by Quora commenter Tevin Davis.
Kureha, for example, is 141 years old, so, may Luffy will live until he's 60. He's a pirate, which means he wasn't planning on living that long.
While the effects of this technique have been mitigated in post-time-skip One Piece thanks to training, the prior uses have already caused irreversible damage to his body. Luffy dies from gear 5th strain on his heart and law gives up his life so they can win. This causes Luffy to go into gears without dying.
So to finally answer your question, the second gear still negatively affects luffy and chips away at his lifespan, but when compared to the time he first developed the technique, the effects are not that great.
Luffy can use Gear 4th for a minimum of 20 minutes, as indicated when he used it against Doflamingo in chapter 785. Luffy never directly tells us what the time limit is, but we see that Luffy & Doflamingo have been fighting for 20 minutes as indicated by the narrator box, so that gives us the minimum amount of time.
It has since been confirmed that Luffy's Gear 5 is set to be shown onscreen on 6th August 2023. His fight with Kaido will also spill into the next episode, which is set to air on 13th August.
5 Shortened Life
While this could likely be a result of the long and hard-fought battle with Kaido on Onigashima and his way up to it beforehand, it could also imply that Gear Five has the biggest strain on Luffy's body out of all.
Luffy Took 10 Years Off His Life by Altering His Own Hormones.
Second while luffy was poisoned by the jailor at impel down and ivankov treated him, ivankov told luffy the treatment would consume 10 yrs of his lifespan.
Gear 2 does. It makes his heart pump faster. Gear 3 only effect his bones and Gear 4 his muscles, nothing that would shorten his lifespan.
1) Kaido. Kaido did in fact lose to Luffy's Gear 5 at the end of the Wano Country arc. However, keep in mind that he withstood multiple waves of strong enemies before this final encounter. Luffy was also completely worn out after the fight and fell into a coma for about a week.
Fan theory suggests that Luffy will awaken Gear 6 in One Piece. The concept of Gears was introduced in the Enies Lobby arc of One Piece when Luffy brought out Gear 2 against the CP9 agent Blueno. His skin turned pinkish and heated up, allowing our main character to move faster.
In addition, Luffy still has his standard weakness to cutting attacks.
Weaknesses. Despite these advantages Luffy is not immortal. Though immune to lightning, he can be damaged by other elements such as fire or ice, attacks involving cutting or stabbing and Haki-infused attacks.
This is very unlikely. Using the ultimate surgery on Luffy would mean that Law would have to die. If it were up to Luffy he would never allow Law to give up his life.
Luffy has lost teeth before in a comedic fashion (Skypeia) and Usopp has lost teeth in battle (Alabasta, etc) and they have always come back.
Gear Second established itself as Luffy's go-to form over time, and it is extensively used by the Straw Hat captain even now in the series.
Nami was one of the first characters to join the Straw Hat Pirates, and remains an extremely important character to the story. When it comes to strength, she's the weakest member of the crew, which is why she often relies on clever tricks and strategies in battle.
Gear 5 is Luffy's strongest form, here are its strongest attacks. Monkey D. Luffy is one of the Four Emperors of the Sea in the One Piece world, a title he received after defeating the strongest creature alive, Kaido, in the Wano Country arc.
Luffy by biting into his thumb and inflating his body through his bones. With the bones growing larger and stronger, Luffy is granted immense strength, capable of shattering a Marine battleship in a single blow.
So, for you manga-readers: yes, Gear Five is in Red. But it's the coyest feature of a major attack I have ever seen in anything shounen.
Naruto vs. Luffy, in Baryon Mode and Gear 5 mode, would probably end in Luffy's victory since he's too unpredictable for the more grounded Naruto to handle. There may be openings and Luffy's lifespan may already be drained by repeated gear use, but Luffy would probably be smart enough to end it quick.
Could Luffy beat Goku in Gear Five? No, he can't. The power scaling in both verses is vastly different: one verse has gone from building to moon to planetary to solar system to low multiversal.