I'm a new 1990 740T owner. I might add an '89 740GL to my stable. I haven't started working on cars but got a Chilton's manual. It covers years '90-'93. Is there a big difference in the '89 and '90's?

If a 940 owner says his AT doesn't always shift into 4th gear; what kind of problem and how serious is that?

Related to this 4th gear problem: (in the 740T) My wife told me the "overdrive turn off" light came on and the car downshifted when she was driving. She didn't hit the button, but she used the button to turn off the light. She was only doing 35-40mph in between lights, probably had just taken her foot off the gas in preperation to slow down. Is that likely the same problem this 940 owner is talking about? It hasn't happened to me...I'm assuming it's not a serious problem.

If there's oil residue coming out of one side of the oil filler cap, I assume there's a slight leak. Is a solution to this a new cap? Is it important? I'd like to keep the professional engine cleaning look it has since I bought it.

I apologize my only contribution to this board is questions. I certainly appreciate all that I read here. Thank you.
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maclords; '90 740T 99,000