Outer Limits 4x4 Board

after drowning my rocky in deep water and getting water into gearbox and transfer case, I have flushed and changed the oil about 5 times now,
I am getting a whine coming from gearbox, only in 5th gear at about 100+kms/hr.
i used castrol epx 80/90 gear oil for both but after looking in the manual it says i should have sae 90 in gearbox and 75w-90 in transfer case.
Does anyone think this might be the cause of my noise or just the fact i got water into box and had to drive home 400kms before i realised?

I'd guess you have damaged at least a bearing, or possibly the wear surfaces on a gear or two. Replacement is the only answer if this is the case.

Try some Redline gearbox oil- that should help quieten it.

Or try a thicker grade of oil

Thicker grade oil will make it impossible to change gears in cold weather without grating or something similar happening. Redline isn't actually thicker.

i got noises in more than 5th.. haha i put some Nulon gearbox additive in mine, i think it made a slight difference.
you say you have used 80w90, that 80 means it is a little thinner in viscosity when cold than the straight 90w oil would be. which isnt a bad thing.

Thicker grade oil will make it impossible to change gears in cold weather without grating or something similar happening.

indeed.

Tufferoza, give the Redline a try. My box is whisper quiet and the changes are a lot smoother. I recently put some in my front diff and the slight noise I could hear with the front hubs locked in is now gone.

I used the Lightweight Shockproof Gear Oil which is supposed to help with cushioning shock loads as well. Around $33 a litre, but well worth the money IMHO. The gearbox takes 2L and the front diff is only 1L.

i do beleive the Redline oil is good, the guy's in the states recomend it in the Mr2 transaxle gearboxes.
having a good run with the Penrite Limslip90 gear oil in my Mr2 transaxle at the moment.

at the moment in the feroza i have some Fuchs stuff i got from work.