I have picked up a 1994 Cadillac De Ville with only 29,000 Km (18,000 miles). It has been babied and regular maintenance, but still, obviously sat unused for long periods. I am taking it in to have coolant flush, oil change and wheel balance (only things that look obvious need attention on it.)

However, I was wondering if I should have the whole oil pan dropped and thoroughly cleaned out. It is three hours of shop time for that, but I don't mind if it is worth it.

The oil looks nice and clean on the dipstick, but I wonder.

Everything else checks out well. But would appreciate any other tips other than mention above that you might do to such a vehicle. Battery is recent, Tires are recent.

Thanks.
Dave.

I would firstly try a good quality filter & synthetic engine oil with good cleaning properties like Pennzoil Platinum in correct weight.
I also would want to confirm good oil pressure indicating oil pump/pick up screen is ok.
Do another oil change after 1000 miles, that should help get things clean.
When storing a vehicle for prolonged periods, fuel stabilizers should be added to fuel and often are neglected. Stale fuel can causes varnish++ issues.
It may best to inspect the tank and take a look inside. Fuel pump & floats & injectors can be effected.
Brake fluid, should be bled/flushed as well. I replace brake fluid every 2- 3 years.

What Tech II said plus:

With that low odometer there isn't any need to drop the pan etc. Unless it has been in a flood, sat many years with the oil cap removed, or had non-detergent oil in it for much of its life. I can't imagine anyone going out of their way for non-detergent oil for this car.

You should to do a transmission service, the drop-pan-then-fill kind. I'd stay away from a flush. Then do it again in a thousand miles.

Maybe drain and fill the power-steering fluid.

Replace belts and hoses, including heater hoses. Thermostat as well. In the process drain and fill antifreeze.

Check tires for rot, and if you plan any long drives think about replacing them or at least know your spare is good and that you can change a tire okay. Especially the rear tires where you have to lift the car way way up to get them out.

Probably a good idea to look for any nests that may have been built and/or abandoned in the engine bay and on the catalytic converter.

Put front on stands and transmission in neutral. Turn wheels all the way one way or another, doesn't matter which way. Slowly turn each front tire while inspecting CV boots for cracks on the stretched-out side.

Check shocks/struts for leaks.

A bit of work, I know, but totally worth it for such a nice car to start off reliable with you.