OK, so I don't own a Caddy. I own an Intrigue with the "shortstar" 3.5L V6 engine. In case you aren't familiar with this engine, it was part of the GM premium engine groupand produces in Livonia, MI from 1999 through June 2002. When GM cancelled production of the 3.5L, production of the Intrigue followed. The engine was dubbed the shortstar because it was spun off of the technology of the northstar engine. Actually, most of the upgrades that appeared in the 2000 4.6L and the 2001 4.0L had been first introduced in the 3.5L engine in 1999.

I arrived at this forum in a round-about way. After chatting on other Olds sites, I came across a problem that someone else with a 3.5L was having. You guessed it. Head gaskets and threads that needed to be repaired in an aluminum block. A google search led me to this website. I am impressed with the depth of information available here and would like to add something as well.

Welcome Olds3.5, great to have you here and I'm sure you can get some input on your "shortstar". I'm fairly new here too and the shortstar is news to me, so tell us about it........Tom

The story of the 3.5L is not a happy one for GM. Before it was decided to ax the Olds division, GM was trying to position the Olds brand as an import fighter. The slogan "not your father's Oldsmoblie" was used, the old image 98 and 88 were dropped and the Aurora and the Intrigue were introduced. The Aurora and the Intrigue used some of the more advanced hardware in the GM parts bin, such as the N* engine technology in the 4.0L and the 3.5L. Specifically, the Intrigue was positioned as an alternative to the Maxima and the v6 Camrys and Accords. As GM's market share continued to slide, it was realized that some major restructuring was necessary. Initially, the 3.5L engine was selected for the Olds division and would replace the 3800 series II engine. After the changes, the 3.5L died and the 3800 lived on. RIP 3.5L (1999 - 2002).

I think our current 3.6L is a spiritual descendant of your 3.5L. It is slated to start replacing the 3800, like you heard about the 3.5L. It also uses Northstar technology.
Right now it's in the CTS and SRX, but will be appearing in the STS and select Buicks in the future.