My brother and I changed the oil in the Buick today for the first time. Its a 1991 Park Avenue with 115K on it. I chose Quaker State Defy 10w30 and the oversized Fram Tough Guard 3980. The filter is not easy to get too, after taking it off the old filter by hand (it was a Purolator the PO had on it), I had my brother stand over the car and hand the new TG to me from above, that was the easiest way. The oil only had around 1000 miles on it but I wanted to get rid of the Purolator, and I figured this would be a good "flush". And indeed it was, the oil came out very dark for 1000 miles so some cleaning was done. One thing I wanted to note was how impressed I was with how quiet its running with this combo. I recommend this oil if you have a GM 3800 and want to try a quiet oil. This seems to fit the bill.