Radiator

I have a 1998 Buick Park Ave Ultra and I have a single core radiator, should this have a dual core one. When I am on the expressway my temp is 189 but when I am sitting in traffic with or with out the a/c on it went up to 218. I have changed the thermostat what do u guys think!!! Thanks in Advance.

Ow...what temp thermostat did you install? I think OEM was 190*, but a 180* is a much better choice. What about your radiator fans? Are they even turning on after your engine is up to operating temp?

When was the last time your rad. system was flushed??? You could have it clogged with misc. crap that is hindering your cooling capabilities. I think a flush and change is recommended every 2 years according to the factory.

This is an old problem but it bugs me, I just got the radiator flushed and a 190 thermostat installed and the temp still gets up to 220 when I am sitting in traffic with a/c both fans are turning but I did notice a single core radiator I have a 98 ultra sc, should this have a dual core?

220 is the point at which most PCM's command the cooling fans to come on, then they shut off again in the 208 range. Heavy duty or SC radiators are probably an option and dont require any additional space, but not necessarily installed from the factory.
A more efficient cooling system will increase engine life and transmission life (as this is cooled as well), but if you're sitting still at 220 and not exceeding 240, you can either:

1) wait until a plastic tank fails and replace it with the biggest option available
2) replace it now with a single core OE part
3) talk to a local radiator supplier and see if a 2 row is available

If it helps, my 3800 Normally Aspirated has a 2 row.