David:
I am sorry to hear of your problem, I am sorry to report that I have the same problem and Toyota wants $7,500.00 for a engine with 75,000 miles. As you might suspect I have not had the problem repaired yet. I even got a second opinion but, with the same results oil, and antifreeze mixed and the coating on the inside of the engine is removed when you allow that to happen.
I was informed if I just had the head gasket replaced that may give me 10,000-20,000 and I would have to replace the engine.
Currently I am looking for a engine for my 1997 LX 450. I would like to contact a lawyer who specailzed in this kind of problem and prehaps bring a class action law suit because of the number of LX 450s with the same problems.
Sorry to be a bearer of bad news,
Clarence the Driver.....