Using heavier gear oil in a super dexta

Goose724 · Dec 27, 2023

I have a Fordson Super Dexta, I'm curious if i can use heavier gear oil in the transmission.

I ended up receiving a bucket of 85w140 gear oil instead of the 80w90 that I ordered, is this okay to use regardless?

if yes, would it also be okay to mix in a slightly less dense oil (1.5 quarts of 80w90) in there to reach the 21.5 spec?

the old oil came out looking like milk, and was very low. (probably like that before I got it) It'll take a while for another bucket of oil to be delivered, should I wait or am I alright to use these?

This post was edited by Goose724 on 12/27/2023 at 08:28 pm.

RandyC · Dec 27, 2023

If it was me I would wait and get the proper oil
if it calls for 80w90. If it had some water in it
I would flush it out before you add the oil.

Majorman · Dec 28, 2023

The Dexta calls for 20/30W in gearbox and hydraulics. It will cause hydraulic failure if you use it in the rear axle sump where the hydraulics draw their oil from. It might be possible but unwise to use it in the gearbox as it could cause hard gear changes and overload an already weak point in the selectors. I would use Universal Tractor Oil. Saying that, I use 20/50W engine oil in all my tractors, engine and transmission/hydraulics, simply because it contains no brake squark control additives that can affect the engines.

Goose724 · Dec 28, 2023

(quoted from post at 02:23:07 12/28/23) The Dexta calls for 20/30W in gearbox and hydraulics. It will cause hydraulic failure if you use it in the rear axle sump where the hydraulics draw their oil from. It might be possible but unwise to use it in the gearbox as it could cause hard gear changes and overload an already weak point in the selectors. I would use Universal Tractor Oil. Saying that, I use 20/50W engine oil in all my tractors, engine and transmission/hydraulics, simply because it contains no brake squark control additives that can affect the engines.

The hydraulics and the gearbox are separate things.
the rear differential is where the hydraulic oil lives.

Majorman · Dec 28, 2023

Goose724 said:
The hydraulics and the gearbox are separate things.
the rear differential is where the hydraulic oil lives.

Yes I realise that, the other problem you may come across in the gearbox is that the Dexta gearbox is pressure lubricated and heavy oil would not be able to travel through the small holes at the base of the gear teeth and pass easily into the bushes and bearings that need it.

Using heavier gear oil in a super dexta

Goose724

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