That is a bunch of crap! I am not pro-Toyota, but engine oil sludge is an OIL problem, not an engine problem. That is SCIENCE, not opinion. Just look at the total number of Toyota engines produced, and then the number with this alleged problem. It is a very SMALL percentage. I am a mechanic with a racing and engineering background. I can tell you for an absolute fact, oil sludge is an oil problem. SYNTHETIC oil CANNOT form sludge unless superheated way beyond the temp a street car can be heated. If you use a PREMIUM SYNTHETIC OIL of the proper viscosity, and change as required, You WILL NOT get sludge. That's a fact.