Why do I keep blowing turbos?

[Tachyon]

During the Spring Cruise, the seals in my 16g were compromised (at just 18psi) and the turbo started blowing smoke like a fog machine. This was unpleasant. Shortly there after, I replaced that unit with a freshly rebuilt 20G and life went on as usual. This turbo felt quite good with 0 shaft play and I decided to run it the rest of the summer on low boost (~22), lest it suffer the fate of my last one.

Fast Forward to last week. After using this turbo for the past 3 months, I started to notice a hint of smoke between shifts. Shit. Before too long I started hearing the all too familiar death whine from the unit followed with an ever increasing amount of oil burnt on vacuum. Last night I started taking it apart and noticed that there is about a 1/4 inch of shaft play and the compressor will touch the housing from time to time. Fun.

I am going to rebuild it before the cruise because 2 minutes of idling will turn the surrounding area into an opaque biohazard zone. I however, need to figure out why I've blown the seals on 2 otherwise good turbos in 1 year.

Here's what I know:

The turbo is fed with a SS line from the Oil Filter Housing. This oil is straight 30 weight changed quite regularly with a wix.

The car is always warmed up for a few minutes before operation, and completely warmed before boosting.

I do not run a turbo timer, but try to refrain from boosting a few miles before my destination.

The oil return line is stock, but appears to flow quite well, although I am uncertain if it's sufficient or not with the supply from the OFH.

The PCV valve does work well, although the system is stock and I am unsure if I should be running more crank evac.

The head is freshly decked and has new valve seals, this is mated to a decked 2.1 with A1's and a Permatorque.

There is no visible oil in the intake manifold or IC piping.

I do not employ a NLTS, Anti-lag, or launch control device.

The plugs look clean, and my AFR's and timing are where I want them on E85.

Anyway, that's what I know. If some of you more turbo savvy guys might have some ideas, regardless how brutal, I am all ears. I just want to learn what I am fucking up so I can waste less money then I usually do on this car. Thanks guys!