Using this Motul engine oil maintenance kit for your Subaru is easy. First, make sure your engine is cool. Then, locate the oil drain plug under the car and place an oil pan beneath it. Remove the drain plug and let the old oil drain completely. Next, replace the old drain plug gasket with the new one included in the kit and reinstall the drain plug. Now, remove the old oil filter and replace it with the new Subaru OEM oil filter. Finally, pour the Motul 5W30 synthetic engine oil into the engine. Make sure to check the oil level using the dipstick. As for maintenance, it's a good idea to change your oil regularly. Keep an eye on your engine's performance and if you notice any strange noises or reduced power, it might be time for another oil change. Also, always store the kit in a cool, dry place to keep the oil and parts in good condition.