If you have no leak it is burning oil.
CONSIDERING THEY RUN HYDRAULIC LIFTERS... YES IT HARD.
Exactly the weight Mazda recommends which is SAE 10w30. Any major brand will be fine.
My Mazda 656 DX 1996 purrs when it's cold. It runs terrible since I moved to South Florida.
Under normal circumstances, 10w-30. If you run in colder weathers, 5w-30.
Perhaps spark plug wires have become porous due to age and are misfiring when they get wet
if you are/have in the past used synthetic oil stop. it will take two or three oil chances to stop this. if you run the motor six to eight hours in summer this will stop this too. the cause is water condensing in the oil compartment
About 4. Then run the engine, turn it off, and check the dipstick.
5W-30 ( if it never drops below freezing 10W-30 should be O.K. )
its in the back of the rear left tire on top
Check the oil first, if oil is low it will run good but just have a constant clicking sound on idle.
If you see 2 lines just above the oil filter that run up the side of the engine to the radiator then yes it doe's.