I just bought a used 2010 Tundra about a month ago with 30,000 miles (5.7L 4x4). A few days after buying it I took it to the local Toyota dealership to have the oil changed. Come to find out, after driving around for 3+ weeks that they didn't fully tighten the drain plug and it has been slowly leaking oil this entire time since the oil change. When I finally realized this and tried to check the oil level, it didn't show up at all on the dipstick. My question is, how many quarts has to be missing for the level to not even register at all on the dipstick? I'm thinking 2 quarts or more (I believe the truck calls for almost 8 quarts total)? Once I realized this the dealership had it towed to the shop so that they could verify where the leak was coming from and replace the missing oil without me driving it anymore. They told me that only 1 1/2 quarts were missing and no damage was done. I'm not sure I believe them. I'm concerned that some damage could have been done driving it for so long with lower than normal oil, perhaps damage that won't happen to a few years and several thousand miles down the road. I got a Toyota for their reputation of being quality vehicles that last a long time. Now I always have to wonder and worry if it will last as long as it would've if this never happened. 3+ weeks of slowly leaking oil, verified by oil spots all over the work parking lot, makes me think more than 1 1/2 quarts were lost. The oil "dumby" light never came on. I glance at the oil pressure gauge from time to time and never noticed it low. Maybe I'm being paranoid? Thanks for your help!