Mazda: overdrive, mazda protege, uk models

Question
Hi Andrew,

There is a overdrive (OD) switch of  my 97 Mazda Protege, I am not sure when should it ON or OFF?
Can you explain what and when suppose use  the overdrive? Also do I need to shift from D to 2 and overdrive off  when the car go uphill or downhill?

Thanks,

Pat

Answer
Deat Pat,
Thank you for your enquiry.
I will answer you question in general terms on the assumption your automatic transmission is similar to that we have on the UK models.
Firstly, unless you have any unusual or specific driving requirements it is sufficient to just let the transmission
make the decisions. You really should not need to shift from Drive to no.2. However,if you were say going downhill in bad road conditions, say ice/snow/very wet etc. By placing the box into 2nd would provide more "engine braking"
and give you better control. I personally do drive like that, but the majority of drivers would never use anything other than D.
As regards the overdrive.
If an overdrive is OFF then you will not have the benefit of an additional gear. An overdrive is a gear ratio over
1 : 1. You would need it ON at motorway/mid to high speed driving speeds, otherwise the engine will be working too fast, and you will use too much fuel.
In the normal course of events, the overdrive should be left
switched ON. It will NOT work until the transmission has acquired a specific working temperature anyway.
This normally takes about 5 minutes.
Switching OFF the overdrive, when you a driving will produce exactly the same phenomenon as I said in answering the question about going from D to 2. You will feel the engine "brake" and should see the engine RPM increase.
If this does not answer your question, do not hesitate to contact me again.
Yours sincerely
Andrew Mooresmith