Ultimately, my question is not "how does engine oil dye work to find leaks" but how would one get past it? How many miles does it last for? How effective is it if it is poured into your oil tank, but then flushed? Will it remove all or the majority of the dye if the engine is not turned on before the oil is changed, particularly if the oil is changed several times? What's left? Will the dye "burn off" the engine after so many miles and if so, what type of mileage are we talking about here? Do any of these variables change with the particular type/brand of dye? The shortened summary is: took the 2005 Scion XA to the shop for a rear main seal fix. Seal had been leaking for two years. Oil leaked approximately 1/2 quart every 3 months at first, and pumped up to about a quart every three months, ultimately. Not a huge leak. Fixed it because we had the extra money. Nothing else major wrong with the car to our knowledge except serpentine belt needed replaced. Corrosion on the battery terminals indicated that we would probably need to have the battery replaced soon, but we'd had no issues with it thus far. Garage did the fix on the rear main. Came up with tons of things that needed fixed additionally. When I asked questions, or suggested that my nephew come to take a look at what he was talking about, suddenly some things 'weren't that bad" or didn't need replacing, that the owner "didn't realize that the part was still okay" and he'd "misunderstood the mechanic". Yeah. Get the car back. Engine light is on. Car makes funky noises when starting. Transmission won't shift from 4th to 5th/overdrive. RPMs running really high. Stay in touch with garage. Oil still leaking. Car throws a spark plug. Have it towed to garage. Garage tells me about the plug. Says leak is because the cap wasn't back on tight (they were the last ones to do anything with it). Says leak is now fixed. Get it back, get the spark plugs off of them. At least one feels oily. Take the car immediately to another garage who tells me that the spark plugs look fine and there was no reason to replace them, although they were obviously not new. One was slightly more worn than the others. The mechanic looked at the car. Said rear main seal was leaking. Said the starter was covered in road grease and dirt, and hadn't been touched. Starter has to be removed in order to change the rear main seal. It clearly hadn't been touched. Garage that did the work is both BBB and AAA certified. The second mechanic suggested I take this to a Toyota dealership to have them certify that the transmission had not be separated from the engine. Toyota said the only way to certify was to effectively remove the entire engine, grab the rear main out and see if it was an original Toyota part. Did report that the rear main seal was still leaking. Called AAA to ask about their process. They came out, had the garage put an oil dye in the car. Made an appointment for the following week. Later called and pushed that appointment back from the Friday, to the following Monday, which made it almost two weeks before the car was checked for the oil/dye leak. During this time, the brake job that the garage had done on my car in September went bad. AAA determiend that it was the caliper. I'd told them at that time that the brakes weren't releasing when I took my foot off the brake. Garage insisted it was because the brakes were bad, no other issues. Caliper turned out to be bad. AAA had them replace that rotor and pad for free, and install a caliper which I paid for with free labor. Other side was not done. Garage kept the car overnight "because they weren't able to get the caliper from the parts store since it was so late in the day". It was around 12:30 in the afternoon. The car had my car overnight. This is after the dye was added to my car. I told AAA that I absolutely didn't trust them with my car. I didn't want to leave it there. He assured me that it would be fine. Two weeks later, I meet with them. I'm *STILL* leaking oil, at the same rate that I had been. They run the black light over the car. No dye shows up. AAA tells me that there is no oil leak. That was six weeks after the rear main seal was "fixed". The car is clearly still leaking oil, but the dye didn't show up. The starter still shows no signs of having been touched, or removed. AAA tells me that this is residual oil, that must be "hung up" or "pooling" in cracks, crannies and crevices with in the engine, and that wind blows it out of the cracks/crevices/crannies and it then drips. He said a few good rains would do it, or it would stop within a few weeks. It's now been since June 13th since the car was checked for the dye/leak, so six weeks. It's been since April 23rd since the rear main seal was "fixed", over four months. I've also had to add oil to the car, coincidentally, at the same loss rate as it was before the car was "fixed". The research that I did on some of the dyes seemed to show that it would last for about 500 miles. I suspect they changed the oil at least once, to wipe it out of there. Or that they did it a few times to be sure that it came out. The car was never started. The dye wouldn't have been flushed through the engine, and it wouldn't have had an opportunity to leak. Any residual, assuming that it wears off in 500 miles, likely wouldn't have shown. That's my assessment based on what I've been able to find. Any thoughts on this? There's a bunch of other stuff going on with my car now, and/or during this process that I haven't mentioned here in the attempt to keep this from becoming an epic novel. Thanks, everyone.