I've been fighting with the turbocharger on my 1.6TD since it's been together. I simply can't get bolts to stay tight on it. They keep working loose in 100-200 miles, enough to need re-tightening. I first noticed it when I heard an awful noise. Only to find the turbo loose from the manifold. So I bought new bolts, lock washers, and red thread locker at lowes. I thought all was well until the sound came back a week or so ago. I found out the bolts had worked their way off yet again. So I picked up two more replacement bolts and lock tighted them back in. Today I find out they're loose again. What the heck?

I have a downpipe that wraps around my engine/transmission, then into a foot long section of flex pipe.
Is there some special bolt that I need to use, because I'm about ready to weld this thing together.