Buick equipped the 2006 Rendezvous with a 3.5-liter V-6 engine standard, with a 3.6-liter V-6 as an option on the CXL trim level. The Rendezvous came standard with a GM Turbo Hydramatic 4T65-E four-speed automatic transaxle. Buick recommends Dexron VI automatic transmission fluid when serving your transaxle.
Checking the transaxle fluid in your Rendezvous isn't as simple as pulling the dipstick and reading the level. To get an accurate reading, the fluid has to be between 180 and 200 degrees Fahrenheit. Temperatures outside that range will give you false readings on the dipstick. Too much or too little fluid can cause damage to the transaxle, so accuracy is imperative. Take your Rendezvous to a service professional if you aren't comfortable with your ability to take an accurate fluid reading.
Buick recommends changing the transaxle fluid every 100,000 miles under normal service and every 50,000 miles under severe service. When the pan is removed and the fluid drained, the transaxle in the rear-wheel-drive Rendezvous holds 7.4 quarts of ATF. The four-wheel-drive transaxle holds 8.1 quarts.