Originally Posted by steve77
I have a Yanmar
(Kanzaki-Hurth) KBW21 gearbox that I had rebuilt in the Azores
. Short story - the rear locknut backed out allowing all the oil to drain into the bilge
. Not knowing if any damage was done to the gearbox internals, I had the disks and separator plates replaced while they were replacing the seals
The mechanic put SAE30 oil in the gearbox. The manual states to use ATF. I tried to ask the mechanic why he put in SAE30, but the language barrier kept me from getting an answer. I do not readily ignore manufacturer's recommendations and I do not know any reason not to use ATF.
So two questions - 1) should I use ATF, and 2) if I pump out the SAE30, there will be some leftover oil in the gearbox. What will happen if I put ATF in the gearbox with a small amount of remaining SAE30?
Thanks in advance!
1), yes do use ATF.
2), I would overfill the gearbox with ATF, rotate it by hand if you can (decompress engine
if possible), drain it out, refill to correct level with fresh ATF, operate for say ten minutes, drain again and finally refill with fresh ATF.
Disclaimer, I am no oil expert but really ATF is still a mineral oil and will mix with other oils. Doing the above will dilute the remnants of the SAE30 to next to nothing IMO.
I suspect the mechanic used SAE30 simply because some other Kanzaki
boxes use SAE30 and that is what he was familiar with.