help me get an advantage as white in this line please

so ive had problems in the past punishing this nonsense line which has gone out of fashion, this is such a 2014 blitz weapon but yeah, any recommendations from the white side ?

d4 or castle

looking for in depth stuff please, not 1 move lines

Just look at the explorer

I would go d4 to attack the center and the black knight. While opening your dark square bishop. Later there is Knight b3 or Bishop g5. Just double-check if you have checks, captures or attacks. And take your time.

A summary of the best line against the Old Steinitz:

take the knight make him double his pawn

Hello

@IM Pfren I was trying to remember this line, I forgot everything past Qd3 lol

7.Qd3 is a key move, and probably all you have to remember.

In the main line you can also go with the same 9.Bg5 plus 0-0-0 plan, but this e5 idea is practical, and strong.

GM dzinzi suggests to take on d4 right away , bd7 and then g6.

its not a nonsense line by any means 
https://www.chess.com/video/player/ruy-lopez-steinitz-defense---part-1https://www.chess.com/video/player/ruy-lopez-steinitz-defense---part-2

There is only one line i think that is theoretically challenging that dzinzi doesnt cover. White plays 6.nc3 g6 7.be3 bg7 8. qd2 nf6 9.Bxc6 bxc6 10.bh6! (you skip f3 till later)

here is some analysis i did on this critical line,

this position is not exactly pleasant for black but it holds.

All these lines are quite passive and problematic for Black. If your aim is suffering, then you are at your element.

The right way to play such positions is the Deferred Steinitz, 3...a6 4.Ba4 d6, as 5.d4 doesn't work now, and 5.Bxc6+ bxc6 6.d4 is not dangerous as Black has not spared a move on ...Bd7.

Or this is nonsense analysis by all means. Whatever comes second.

His plan of 4...exd4 plus 6...g6 is met effectively by many means, e.g. 7.Bxc6 bxc6 8.Bf4 when White is just better. Faithful to his style, Dzindzi mentions only 8.f4 and hides Bf4 under the carpet.

i fail to see the big threat promised by bf4. 8.bf4 bg7 then what? 9.qd2 nf6 10. e5 nh5 so im assuming you mean to play Bh6 idea but this just transposes to the "critical line" i mentioned above.
the line after re8 has only been reached 10 times, and all from games before the year 2000 results were 50% draw 33% white wins 17% black wins. Of course white has advantage but even the computer line 20 moves deep only gives white a 0.6 advantage. I agree Dzinzi is overestimating the equality black can get agaisnt critical lines, but this is def holdable. White has to really think twice before pushing for f4 when the knight on e5 is a fantastic resource.

I think the old steinitz suffers from a case of being more ugly than bad. A lot of the most common lines are "crooked" even if eval wise black should be fine. Combine this innate ugliness with the fact its played a lot by weaker players who dont know any theory (something the philidor also suffered from until its relative comeback recently) and the fact people write it off in favor of the steinitz deferred, which usually plays differently, and you get a very underrated defense.
To play it well you need a very high understanding of positional dynamics to not end up in a worse endgame. you have to maximize the flexibility of your doubled pawn center and the b-file and hopefully not give up the bishop pair too quickly. But almost no one knows the most critical lines and even those allow black to hold. Its just a very crooked acquired taste.

No. The reason Bf4 is better than Be3 is that after 8.Be3 Bg7 9.Qd2 Black can play 9...c5!

With the bishop at f4, 9...c5 fails to 10.Nf3.

Also, the preliminary f3 (instead of Bh6) is fine with the bishop at f4, as ...c5 doesn't work very well again.

i think the problem here (on the f3 line) is that black should 0-0 and possibly play re8 before c5. if white now plays bh6 early, e5 is no longer a threat and if he begins his pawn storm early, black can begin his own counterattack with qb8 and the b-file.
if white doesnt play 10.f3 as mentioned above or 10.bh6 (transposes to my critical line), the other main possibility is 10.0-0-0, but ng4! almost immediately equalizes. For example. 10.0-0-0 ng4 11.nf3 f6 12. h3 ne5 and we have another position thats more crooked than bad.