[GuidoK]

Sure if they can't handle the workload. But I dont see why one shouldnt be honest with a customer (or person in general). Just tell them so.
TBH I think for these kinds of jobs you're better off with a real specialist. They usually have more experience, more care for the customer and are way cheaper.
In germany you can get this service, incl all the parts (bearings, bolts, gaskets, oil filter and tws oil change) for €1080, or €1120 if you need a new oil pump relieve valve piston (they wear too), so thats about $1390,- (and thats including the 20% tax that you have to pay in europe as a private person) to give an idea what a service like this should cost.