On a 2006 Mazda 6 where is the dipstick for the manual transmission?

 

No, as far as I know, there has never been an automotive manual transmission with a dip stick from any manufacturer anywhere in the world.

 

Oil level is inspected via the fill plug.

 

I am not sure what I am looking at in the diagram. Where is that plug?

 

Fill plug is in the gearbox.

The diagram shows the gearbox looking from the front of the car( as if you were between the radiator & gearbox), you can see the LH driveshaft in the background.

 

Next question: is the fill plug something I can remove with my Sears Craftsman socket wrench? I ask because I cannot remove the drain plug from the engine's oil pan. My mechanic tells me that the oil pan is aluminum and the drain plug is steel, and one needs professional tools to unscrew that plug. I wonder if I will have the same difficulty with the fill plug of the transmission.

 

23mm ring spanner or 23mm 1/2" drive socket & power bar.

 

You will likely need a new aluminum crush washer if you take that plug out... Look up the size and have one ready. Much cheaper to get a small bag of them from amazon $5 vs. $3 for one at the auto parts store... My car uses the same size washer for engine oil and auto trans drain plug... (2010 6i 5sp auto). Also be sure not to over torque and damage the threads when putting it back. Get a torque wrench...

also the level will be higher if the oil is warm/hot. Not sure what temp Mazda specifies to check the level... have a pan or bucket underneath and be prepared for some to leak out.