Hi BITOGâ€”longtime lurker, first time poster here. I am grateful for this community. I'm posting because I'm bewildered by the difference in recommended OCIs between my two cars. I've always been a Honda guy but recently got my first Prius. So currently my cars are a 2004 Pilot and a 2005 Prius. The Prius has a manufacturer recommended OCI of 5k miles, changing the filter every time. The Pilot has a manufacturer recommended OCI of 7.5k miles, changing the filter every 15k miles. This just seems wrong to me. I would expect it to be the other way around, if anything. Surely the Pilot is harder on the oil than the Prius with the same driving conditions? I live in WI and both cars get mostly highway miles w/out towing, so pretty gentle driving conditions on the whole. I'm using quality high-mileage synthetic oils (Mobil 1, Quaker State, Valvolineâ€”whatever's available and cheapest when I'm shopping) of recommended viscosity on both engines, OEM filters, redline in the gas before each oil change. I don't think I'm willing to drop $30 every few months on each car for habitual oil analysis, although I might be persuadable. The Pilot has 198k miles and the Prius has ~312k (the odometer stops at 299), if anyone cares. So: I'm looking for opinions on the manufacturer recommended OCIs for these two cars, any suggestions for me to help get the Prius to 400k and the Pilot to 300k :), and any opinions about WHY there's this disparity between the recommended OCIs on these cars. Thanks!