You might check out Carmelo Patti's joint, right there in Mendoza City. He's pretty old school, to the point of being one of the fathers of oxidative winemaking practices, way before anyone was talking about aging in amphorae.
There aren't a lot of wines that don't show vestiges of the winemaking, but it's not as bad as it was even five years ago. Lots of modern approaches are apparent, but cut them some slack; it's only recently that they've had any capital to work with, plus there's only recently been any sort of tradition where the winemakers would work (or go to school) in places other than Mendoza. If this is your first trip to Mendoza, spend a day in Maip (you can rent bikes from
Bikes & Wine and get some exercise) and visit the winemaking museum at Bodegas la Rural (
http://tinyurl.com/yles525), have lunch at Almacen del Sur (
http://www.almacendelsur.com/) (sit inside and do the full fancy lunch, not the biker's lunch), and just stop at any winery along the road that looks interesting (Zuccardi is worthwhile, despite its enormity).
Better yet, spend a couple of days south of Mendoza. Lots things to experience. Chacras del Corio is a cool suburb to spend time in (at least a couple of degrees cooler than the city), with a great art gallery (Mucha Museum), restaurants and a shop called Ayllu which is where you'll want to buy any souvenirs you'd want to take home from the trip. Alta Vista (
http://www.altavistawines.com/) is French-owned and they're doing a really good job of balancing French attitude with what works in Argentina. Vistalba (
http://www.carlospulentawines.com/) is nearby too, and you owe it to yourself to go to the restaurant at the Vistalba winery called La Bourgogne. Impressive food from some guys who really know how to cook (and source ingredients).
There is no lack of wineries in Tupungato...Salentein, Andeluna, Clos de la Siete, J&F Lurton, et al are down there. Most importantly, you need to stop at La Posada de Jamon (
http://www.laposadadeljamon.com.ar/). It's a wonderful place, unless you're a pig. If you're not a fan of pork, hit El Hilo right downtown. It's a seafood place (most comes from Chile) that's quite good. It's worth going there for the queso fresco.
If you really want to get away from it all, I strongly recommend a day or two at Estancia Rancho Cuero (
http://www.ranchoecuero.com.ar/). It's kinda in the damn Andes and you go horseback riding, eat lots of meat, and have a great time away from whatever passes for civilization.
Having been there several times recently, my advice would be to not worry about whether a wine is old style or new, and just enjoy the energy of a wine region in transition. Stop into the Vines of Mendoza wine bar and taste through a bunch of stuff. The staff there knows their stuff and should be able to steer you to wines you'd like.
-Eden (everyone I know who's visited Argentina now wants to move there)