English (common) oak is considered too harsh for wine. French and American oaks are specific varieties, not simply common oaks that grow in those countries. I have used both and didn't notice any difference. Oak chips come in various forms, from virtual sawdust to small cubes. Ideally, red wine should be matured in oak casks. Due to the porous nature of wood, the wine slowly breathes oxygen as water evaporates and air is sucked in to replace it. The wine in contact with the oak slowly becomes smoother as a result of changes in the tannin content and the flavour changes. After initial racking, the wine is transferred to casks without fining. A fairly small deposit of yeast slowly reacts with the cleared wine and improves the flavour. Finally the wine is bottled, where further improvements take place. Simply adding a handful of oak chips per gallon during fermentation has little or no effect. However adding about 15 g per gallon of red wine and allowing it to clear naturally does make a positive difference if no cask is available, but the slow breathing will not occur. This can be simulated by periodically racking, rinsing the yeast out of the chips and putting them back. After bottling, the wine should be left undisturbed for the final maturation process to complete. Wine matures better in bulk, so 5 gallons will give a better result than 1. A new 20 litre oak cask, complete with bung, stand and tap will set you back about ã100, little more than the cost of a 5 litre cask, which I do not recommend due to the faster rate of evaporation.