changine oil is very similar on any cars. check your owners manul for the amount of oil that is needed, and the proper grade and it may actualy say the grade need right onthe cap it self. right under the engine is an oil pan and there should be a drain plug and thats how you ge the oil out. there also will be a filer in that area as well. ive never work on a HHR or and 2.2 ecotec engine some im not positive. somethign else that helps would be to go on google or a search engien and type in how to change engine oil. hope that helps chief