I see no basis for such a ridiculous statement by that non-owner about long distance and heat, makes absolutely no sense. What you should be aware of in your settling on a used BMW is the "NikaSil" (I think I've got that right) problem that particularly affected the 4.0 liter V8 engines. The problem I believe was that high sulfur content gasoline in North America reacted with the cylinder sleeves leading to scoring of the cylinder walls, essentially failure of the engine. BMW made good on some engine replacements, but I think have long since discontinued doing that. I don't recall when or how the problem was finally rectified, but I think it existed into the mid-90s anyway, perhaps longer. So you should do your homework on the model or particular vehicle history, or better yet just avoid the V8s and stick with the far better proven, highly durable, and more fuel efficient I6s.