Having lived in cold climates, I would recommend that you either keep the stock oil/water cooler, or if you have to go with an oil/air one, use an oil thermostat inline with it to allow the oil to warm up properly. I actually like the stock oil coolers that Porsche and also VW used; I bought an '84 GTI without an oil cooler and added a stock one from a GLI. Not only did peak oil temps go down, but the oil got up to full temperature much faster. Lets you beat on it that much sooner
If you allow an oil/air cooler to have full flow all the time, the oil may never hit a proper operating temp in the winter...
just one guy's opinion...
nate