over-filling manual transmision?

[victor_t]

I changed the manual transmission oil, and I know I probably over-filled the transmission a bit, probably put in half a liter more than needed.

I am wondering if this can cause any damage. What happens if the oil level in the tranny is higher than it should be?
Basically, do I bother draining it to be level with the fill hole or leave it as it is?



Also, about oils: does it have to say on the bottle that it's for manual transmission? On the bottle it said "gear oil", and it's a synthetic GL5 75w-90 oil. since GL5 75w-90 is the proper spec for the transmission, I assume the oil is good...

[Flagrum_3]

I don't think it's possible to over-fill the manual tranny as the bottom of the fill hole is your level.If you put too much in it would have just drained out the same hole.....So don't worry about it!

GL-5 75w-90 gear oil is the correct stuff.


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[Walrus]

It should be GL-4 or GL-5. However, if you put in GL-5, it should say it is for manual transmissions with syncros. Regular GL-5 gear oil, which it sounds like you used, is intended for differentials, and will possibly ruin the brass syncros in your transmission.

What specifically did you put in? Brand, complete spec etc?

[victor_t]

well, first of all, the car was not level, the front tires were on some wood planks so the car was probably on a small incline (not sure about the garage floor)

also I had spilled some oil initially (0.5 liters) and I made up for it after :)
I poured a total of 4 bottles and about half a bottle had spilled on the floor.
when the last bottle was getting poured, oil started leaking out of the transmission at the end of the bottle.
When I tool the plastic funnel out oil was still pouring out from the bottom part of the fill hole. I didn't wait for it to stop before I put the plug back in. so I know I have some extra in there. less than half a liter extra due to the oil pouring out, but still...

[victor_t]

It should be GL-4 or GL-5. However, if you put in GL-5, it should say it is for manual transmissions with syncros. Regular GL-5 gear oil, which it sounds like you used, is intended for differentials, and will possibly ruin the brass syncros in your transmission.

What specifically did you put in? Brand, complete spec etc?

from the bottle
motomaster synthetic gear oil 75w90
meets API GL-5 and MT-1, Mack GO-H and MIL-L-2105D, MIL-PRF-2105E specifications. can be used where API GL-5 80W80 is specified.

[kevcol74]

If you happened to put extra in, you risk blowing seals. I doubt you will have the problem, but if you can level the car and let the excess drain, that would be better.
Simple physics at work here, oil heats up and expands. If it heats up more oil than there should be in there, it can litteraly push out the seals. Same idea as overfilling your crankcase with oil, it can blow out seals.

[Cosmo77]

if your only about .5L over then you are probably fine...the Mazda3 tranny's are just a progression of the Mazda 5spd tranny that came out in 1986. Other than some syncro design changes, and obvious gear selector changes (shaft to cable), it is the same thing inside. I would recommend that you drain out the extra oil though, just to be safe.

Cosmo

[Flagrum_3]

if your only about .5L over then you are probably fine...the Mazda3 tranny's are just a progression of the Mazda 5spd tranny that came out in 1986. Other than some syncro design changes, and obvious gear selector changes (shaft to cable), it is the same thing inside. I would recommend that you drain out the extra oil though, just to be safe.

Cosmo

+1, agree to a point.If you are out .5 litres (+/-) it should not cause any ill effect as manual transmissions are not as pressure sensative as say auto transmissions on the plus side.There is quite abit of 'pressure-threshold' build into the design.

GL-5 gear oils as of late, several years now in fact, are perfectly safe for 'yellow-metal' components such as some syncromesh gear types, so you would be perfectly fine...GL-5 is also recommended in the Owner's manual.

You might be better off though trying a quality gear oil such has Redline Synthetic 75w-90ns for far better 'feel' and 'protection'.It is always best when doing a drain/refill to have the vehicle as level as possible, preferably jacking the car up on four stands instead of 'ramping it'.


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