I'm going to look at an '05 STS (Northstar) which has been sitting outside (on paved surface) since its owner passed. Quite low mileage. My concern is are there particular areas I should inspect. Aside from the old gas, what should I do before attempting to start it? I'm concerned about a lack of initial lubrication after 4 years sitting. It has the Deathstar, since it is rear wheel drive and the engine isn't "sideways", can I assume repair is less a problem than with front wheel drive versions? I understand most head gasket issues were solved by '05, correct?

I would ask about a Caddy on a Caddy forum, not on here

Sitting outside in Mass for four winters? That has to be a little rough on a car. Those were nice cars when new but four years is a long time for a car to sit outside in the elements. Most likely have rodent damage, brake system is probably rusted out and the fuel system is shot. Exhaust could be rotted out too.

Failure rate might have gone down over time but it was still an issue. I had the chance to buy a mint low mile one a couple years ago and I don't even know if even thought about it before saying no. Those Cadillacs are interesting and can be nice to drive but one repair can cost more then the car is worth and it's not if it's going to break but when. If it's free or cheap and doesn't have anything wrong with it might be fun to mess around with but the second it breaks take whatever you can for it and run.

2006 was the year they fixed the head gasket problems.

Would have been one thing if it sat in heated storage for 4 years, but outside? Whole other animal as the guy above stated.

I’ve heard that oil pumps can be a problem on these thingsGood luck!

I think your biggest issue might be the fuel injectors being possibly gummed up. Beyond that I would get as much gas out as you can and put some fresh fuel in and fire it up. If the injectors are fine and rodents haven't eaten any wires it will likely start up like you turned it off yesterday. I would expect some tapping for a little bit but I bet it doesn't last long.

Besides the issue with the head bolts pulling out of the block (due to block porosity) despite several iterations of different thread pitch and aftermarket stud installation, it remained a problem to some extent throughout all of production. I'd pass on it but if you try to start it, be aware that these engines are also know for losing oil pump prime. The solution was to way over fill with oil till it primes, then remove excess oil. Some would even lose prime during an oil change, others would lose prime if sitting for an extended period of time. Brake lines are most likely severely rusted and ready to fail.

Fire it up and see what happens🤔 You may get lucky..

Knowing its a GM was all I needed to know. The rest does not matter.

Knowing its a Caddy STS is all I needed to hear.
It looks really good sitting where it is, from here.
The good news is IF it still has converters on it, they could be worth some pretty big bucks scrap value.

The starter is under the intake. Head gasket problems. Heater core problems. I would take it if was free.