You'll clog up filters until all the gunk and buildup in your fuel system is gone. It all depends on how much there is in the system. My wagon wasn't bad at all. I had one really bad filter and that was about it. But I put one tank of B50 into my 240 and I clogged up the filters real in 200 miles. So it varies from one car to another.

White smoke on start up might be a bad glow plug. If one is bad that cylinder won't burn as well as the others when cold. So you might check your plugs. But, a little smoke on start up is normal. If it goes away shortly after I wouldn't worry about it. But if it start billowing out and won't go away I would be worried.

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