Just for discussion -- I'm trying to understand this. What about fuel injection has made the flame trap irrelevant? The only difference I can think of is the float valve in a carb might be a little less resistant to the pressure wave and flame front from ignition when an intake valve happens to stick open, or ignition occurs at the wrong time. How does that affect the communication with the crankcase and its volatile mixture?

A rumor of a service bulletin removing the flame trap? That we should look into. Figuring Volvo to have a few lawyers around, I can't think they'd be more sympathetic to poor oil change habits at the expense of safety. I'm saying that with a rather fresh memory of EZK screwing up and hearing that pop through the carburetor - er - throttle body that causes me to cringe. Yes let's find that service bulletin...
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Art Benstein near Baltimore

Milt Famie was a pitcher for the Cubs. Unfortunately, he had a great fondness for beer. After walking several successive batters in the 9th inning, the manager of the opposing team turned to one of the batters asking what that was all about. Said the batter "It was the beer that made Milt Famie walk us."