I have a 04 MCS, 150k miles. I haven't been the best about giving it the TLC it needs, but I've realized that it's getting grumpy at me, and if I don't do something soon, it'll get worse. Over the last month or so, I've noticed my oil light come on at idle if the engine is warm. Once it's warmed up, when my engine gets under about 1000RPM, my oil light turns on, if I rev up my engine above 1000, it turns off, once the rpms fall back under 1000, it turns back on again. I've checked my oil level, at first it was a bit low, so I added 1qt of Mobile 5-30 synthetic high mileage, got it up to level, but that didn't resolve the issue. (yes, my mini leaks a bit of oil). Last week I got the correct socket to pull off my oil filter cover. I visually inspected the filter, no signs of collapse. I have the "new" filter cover where the filter has the built in reinforcement. The rubber rings on the filter were facing towards the block. I used my cell phone camera to look where the filter cover connects, and it looks like the spring is intact. My oil was last changed about 3 months ago. I recently had a problem with my drive belt snapping, I traced back the cause to a bad idler pulley and a bad tensioner/damper. I replaced both. Engine now runs smoother, however my engine still doesn't sound healthy. I suspect I may need to replace my timing chain tensioner. Do anyone have thoughts on what else I should check? Edit: I also have access to a full set of electronic diagnostics if any of them will help.