First time post. My 2008 Range Rover HSE currently has 125k miles and has started to “roar” slightly when I accelerate (i.e., RPMs go up but torque and acceleration is delayed). It is drivable and not terrible right now but could be getting worse. I am not mechanically inclined but assume it might be the transmission. I’ve owned the vehicle since new and records from my independent mechanic (now out of business) shows a “transmission service” for what looks like 4 Quarts ($44) and labor ($38) that he did with the scheduled 105k mile maintenance service 4 years ago. Customer complaint was “transmission periodically slipping.” I’ve read many of the transmission fluid drain and filter change posts on this forum which are very helpful. I realize transmission fluid/filter change is preventative maintenance and not generally a repair. But my question is whether the “roaring” sounds like a transmission issue that might be helped with the fluid/filter change? I could do that myself. Based on my records/memory, I assume the fluid was just drained and refiled 4 years/20k miles ago. Maybe the filter needs to be changed anyhow or maybe I just need to check to see if the fluid is low? But didn’t want to incur that cost/labor if I was going to have to find someone inspect or do a major transmission repair anyhow. My iCarsoft Tool (CRPro) shows no faults. Any thoughts would be very appreciated about potential cause, and my next best move?