Gear oil query

[Monkeybusiness]

Right then chaps - I’ve popped a core plug out of my mulcher gearbox (1000rpm pto input - double output, 150hp, constant load changes).

Fortunately I discovered it before very long and it was still largely full of oil, so I’m happy that it should all be ok mechanically. I think some contamination may have got into the oil (woody material) so I was going to drain it in the morning and refill with fresh.
I’ve made a plate to bolt to the 4x holes that I’ll silicon on to finish this job. Should I flush the gearbox with anything once drained before refilling? Diesel/carb cleaner etc?.
I can’t find the manual so was wondering which of the following gear oils you would suggest chucking in? It only needs to do a day tomorrow and can then be drained/refilled with the correct oil when I find out what that is!...
I have various quantities of the following - can they be mixed? What does GL4 or GL5 mean? They all look/feel/smell/taste the same....

 

[jd6820]

80W90 GL5 would be my choice. The others in the following order: EP90, EP80, 90LS and then 85W140

That gearbox will probably be spec'd for 80W90 or EP90, I wouldn't worry too much about the GL rating. No bronze bits in them to my knowledge or at least owt that'll take any harm

Simply bearings will sort you a plug to suit. It's a generic part that's dirt cheap. As for flushing, just pop cap off and flush with a bit of diesel before refill.

 

[Shovelhands]

Is the breather blocked? And thus why it’s popped the plug out?

 

[Monkeybusiness]

Is the breather blocked? And thus why it’s popped the plug out?

No, it’s been smashed in. It’s not round any more (can’t see that in the pic very clearly though).
Now I’ve seen how fragile it is I’m amazed it hasn’t happened before tbh! The steel plate repair will be a permanent addition over the top of a new plug.

 

[Monkeybusiness]

80W90 GL5 would be my choice. The others in the following order: EP90, EP80, 90LS and then 85W140

That gearbox will probably be spec'd for 80W90 or EP90, I wouldn't worry too much about the GL rating. No bronze bits in them to my knowledge or at least owt that'll take any harm

Simply bearings will sort you a plug to suit. It's a generic part that's dirt cheap. As for flushing, just pop cap off and flush with a bit of diesel before refill.

Thanks for this. What is GL4 and GL5? (Is GL5 a higher spec?). Would the EP80 GL4 and EP90 GL4 be alright if combined or is that asking for trouble?
The 85w140 was for a Ford Ranger limited slip diff I think (it was bought specifically as I was told not to use standard gear oil for whatever reason). I assumed it was a really high spec?

 

[Gecko]

Tracking down oil specs is a real rabbit hole where you can get lost for hours.
With EP or Hypoid spec, it's about extreme pressure additives
With LS oils, it's about what isn't in the oil as it is for limited slip diffs.
Wet brakes are another place where it's more about what isn't in the oil

GL5 has more EP additives than GL4 making it better suited to shock loads, but unsuitable if you have bronze components (typically bushes, thrust washers and synchro-rings )

My feeling is that you are not going to corrode anything in 24hours and I'd rather had a heavier oil than lighter.
As for draining, I wouldn't add anything to to thin the oil as it may deteriorate the seals. Ideally, drain it when warm.

the-differences-between-gl-4-and-gl-5

 

[Monkeybusiness]

Tracking down oil specs is a real rabbit hole where you can get lost for hours.
With EP or Hypoid spec, it's about extreme pressure additives
With LS oils, it's about what isn't in the oil as it is for limited slip diffs.
Wet brakes are another place where it's more about what isn't in the oil

GL5 has more EP additives than GL4 making it better suited to shock loads, but unsuitable if you have bronze components (typically bushes and synchro-rings )

My feeling is that you are not going to corrode anything in 24hours and I'd rather had a heavier oil than lighter.
As for draining, I wouldn't add anything to to thin the oil as it may deteriorate the seals. Ideally, drain it when warm.

the-differences-between-gl-4-and-gl-5

Superb, thanks for this. Makes sense, that’s great!

 

[V8Druid]

having just bought 20 l of EP100 for me lathe's geared head and screw cutting box (EP = extreme pressure), I personally would be going for the 85W140 as the oil in there is going to be getting quite a bol***king .... but EP 90 also stands up to serious grief in diff.s and drive hubs, so just about any of those should stick the pace for the short term until you can establish what is supposed to be in there.

 

[Left hooker]

We use ep 80/90 in lorry gearboxes and axles , digger slew reductions and pilot pumps and track motor reductions so would say it will be fine with that

 

[Monkeybusiness]

Spoke to Teagle this morning and they said EP90. I asked about GL4 or GL5 and they didn’t know the difference...

 

[Left hooker]

Spoke to Teagle this morning and they said EP90. I asked about GL4 or GL5 and they didn’t know the difference...

They are only up the road from me those flails are bought in and badged as teagle

 

[Left hooker]

 

[Monkeybusiness]

They are only up the road from me those flails are bought in and badged as teagle

Yeah, it’s a Berti (they don’t pretend otherwise).
Good bit of kit, it’ll happily take down 12 inch standing trees.

 

[Left hooker]

Yeah, it’s a Berti (they don’t pretend otherwise).
Good bit of kit, it’ll happily take down 12 inch standing trees.

Dad would have had us saving that trunk for logs