I have to replace the engine in my 2006 HHR which is a 2.4 litre with an oil cooler. Can I replace the engine with the 2.4 litre that does not have an oil cooler that was put in the HHRs the later part of 2006?
Technically speaking you should be able to. Swap the parts over for the oil cooler from the old engine to the new one. If the new engine didn't come with an oil cooler, its ok not to hook it up. I would try to make it work especially if it is a force inducted (turbo/supercharger) model. If not, it should be ok.