You likely can have it done cheaper by and independent mechanic. Getting the work done is only necessary if you want to avoid being suddenly and without warrning, stranded in the middle of nowhere and find you have done far more than $1,000 of unnecessary damage to your engine.
Yea, this one is necessary. Consider it on a cost per mile bases, $1,000 divided by 100,000 miles equals 1? per mile. How many cents per mile do you pay for fuel?