diff --git a/lib/auth/oauth2client.js b/lib/auth/oauth2client.js
index 3eccdfa..ab01bad 100644
--- a/lib/auth/oauth2client.js
+++ b/lib/auth/oauth2client.js
@@ -22,6 +22,7 @@ var noop = require('lodash.noop');
 var PemVerifier = require('./../pemverifier.js');
 var querystring = require('querystring');
 var util = require('util');
+var DefaultTransporter = require('./../transporters.js');
 
 var certificateCache = null;
 var certificateExpiry = null;
@@ -35,7 +36,7 @@ var certificateExpiry = null;
  * @param {Object} opt_opts optional options for overriding the given parameters.
  * @constructor
  */
-function OAuth2Client(clientId, clientSecret, redirectUri, opt_opts) {
+function OAuth2Client(clientId, clientSecret, redirectUri, opt_opts, transporter_options) {
   OAuth2Client.super_.call(this);
 
   this.clientId_ = clientId;
@@ -43,6 +44,7 @@ function OAuth2Client(clientId, clientSecret, redirectUri, opt_opts) {
   this.redirectUri_ = redirectUri;
   this.opts = opt_opts || {};
   this.credentials = {};
+  this.transporter = new DefaultTransporter(transporter_options);
 }
 
 /**
@@ -152,7 +154,7 @@ OAuth2Client.prototype.getToken = function(code, opt_callback) {
     }
     var done = opt_callback || noop;
     done(err, tokens, response);
-  }, this.opts);
+  });
 };
 
 /**
diff --git a/lib/transporters.js b/lib/transporters.js
index 82f0a0b..613d182 100644
--- a/lib/transporters.js
+++ b/lib/transporters.js
@@ -24,7 +24,9 @@ var utils = require('../lib/utils.js');
  * Default transporter constructor.
  * Wraps request and callback functions.
  */
-function DefaultTransporter() {}
+function DefaultTransporter(options) {
+  this.options = options || {};
+}
 
 /**
  * Default user agent.
@@ -54,9 +56,9 @@ DefaultTransporter.prototype.configure = function(opts) {
  * @param {Function=} opt_callback Optional callback.
  * @return {Request} Request object
  */
-DefaultTransporter.prototype.request = function(opts, opt_callback, extra_opts) {
+DefaultTransporter.prototype.request = function(opts, opt_callback) {
   opts = this.configure(opts);
-  opts = utils.extend(opts, extra_opts);
+  opts = utils.extend(opts, this.options);
   return request(opts.uri || opts.url, opts, this.wrapCallback_(opt_callback));
 };