Toyota Repair: engine flush, 1991 toyota camry, toyota camry

Question
I just purchased a 1991 toyota camry le 4 cylinder.
The engine is very dirty because the previous owner did not change the synthetic oil for about 20,000 miles.  Can you recommend engine flushes I can purchase to clean this dirty engine.  One of my mechanic told me to put 1/2 quart transmission fluid in the oil and run for 3000 miles, drain and refill.
What do you think.  I appreciate your opinion.  I would like to keep the car; it has 135,000 miles and runs well except for the dirty engine.

Answer
I don't have any way of knowing how badly the engine is sludged up but I guess you can try adding some sort of additive to remove some of it, there are some repair shops including some toyota dealers that have an engine power flush machine, I suggest that you try to find someone that has this machine, they work very well in getting rid of internal engine gunk, good luck.