I change my oil and filter every 10,000 kms, along with a chassis lube. I just did a complete lubricant and filter change on the weekend at 40,000 kms. I was using Mobil 1 Delvac 5w-40 but it seems to be back ordered here. So I switched to Petro Canada's Duron 5w-40. The trans and t-case got Mopar ATF+4. The diffs got Mobil 1 Synthetic 75w-90. The engine oil and fuel filters were from Cummins and the trans filter was from Mopar. Total cost was about $200.00 CDN.