I just bought a toyota sienna 99 with 101,200 miles, after drive it a couple of blocks a noticed the engine oil signal start to flicker and then goes steady, i decide to add an quarter oil, then drive it some other distance and the same thing happens, then add another quarter oil, It happens again and the same thing but I drove about 100 mi that way. long story Ha.., Some how this is related to the sludge engine build up you guys talk about in this tread? or shoul be a sensor issue, any help will be greatly appreciated.