I have a 2013 Nissan Altima 4 cylinder with a CVT transmission. I have never checked the fluid level because the transmission dip stick has a seal on it that has to be broken to pull it out. I have a Nissan published maintenance schedule that I downloaded from the internet. It has recommended service intervals (miles/months) for various routine maintenance procedures (oil change, air filter, brake pads, spark plugs, coolant, etc.), but has nothing about changing the CVT fluid - it just says to check it whenever performing other maintenance (but never says when to change it). The car now has 51,000 miles on it. Is it past time to get the CVT fluid changed? I always had the fluid changed @ 30,000 miles in vehicles with conventional automatic transmissions, but all of the other maintenance procedures on this vehicle are required much less frequently (ex. - spark plugs & coolant @ over 100,000 miles) than what I always did on previous vehicles (usually 30,000 miles for above examples). .