I haven't driven my SC430 for about 2-3 months I started it last night and herd some pretty bad noises, sounded like valves. Is there a correct way of starting the car after it has sat for a long period? Do you think I did any damage?

 

All the fluids settled from lack of use. The sounds should go away after about 15 minutes of running.

It takes a lot more than not starting for a few months to cause damage, a LOT more.

Don't worry.

Is the car stored in a very cold area ? If so, you may want to consider a "block heater". This will keep the internal fluids (oil) at a mean temp so there won't be a strai when you start.

 

The car is stored in a garage attached to house. The only side of the garage exposed to the outside is the door, the rest is surrounded by the house. Further, the door isn't opened unless I need to get to the car so I think it should be warm enough. What do you think?

 

Sounds like it should be warm enough. Best bet is start the car at least once a week and let it run about 10 min.

 

What I do with mine is once a month, during the winter, I take the car out on a 10 mile run. That is 5 miles out and 5 miles back to the house. Only on dry days, ie no rain or wet roads. That not only gets the oil thinned out but lubricates bearings, etc. In addition it keeps wheel bearings lubed, transmission & differential lubed. Then in the spring I put the top down and go cruising. I have never had any problems using this method.
Ron