Last week, my 87 240 did something it never had before. The transmission lagged in it's shifts letting the engine rev higher than normal before next gear engagement. It did this on just one short drive with a warm start. It hasn't done it since. I properly checked the trans fluid level (with the car well warmed) and level was normal. I don't have experience with automatics, but the fluid looks a little past due for a change. It seems that a flush and refill is in order. But here's the thing...I'm about to take the car on a 1000 mile trip up north. Should I wait to make the change or go for it and take my chances the new fluid will expose a past due rebuild and leave me stranded? It only has 120,000 miles on it but it may have been neglected. Thanks for any input.