Gearbox/FD oil GL4 ?

[hughguzzi]

Just wondering - I get my gearbox and FD oil from a BMW independent and have simply used what was sent - Millers EP 80w90 GL4 mineral transmission oil. Now as far as I know so far its been fine but when looking in the Haynes manual I noticed it states SAE 80w90 'Hypoid gear oil API GL5'
Just wondering why a knowledgeable dealer would supply an oil not up to the spec in the manual ? I dont want to question the dealer and seem like a dumbass !!!

 

[Timolgra]

Use GL5

 

[uncle dick]

Not as knowledgeable as you thought...

 

[Deleted account 250319001]

Just wondering - I get my gearbox and FD oil from a BMW independent and have simply used what was sent - Millers EP 80w90 GL4 mineral transmission oil. Now as far as I know so far its been fine but when looking in the Haynes manual I noticed it states SAE 80w90 'Hypoid gear oil API GL5'
Just wondering why a knowledgeable dealer would supply an oil not up to the spec in the manual ? I dont want to question the dealer and seem like a dumbass !!!

My Local independent did the same. I told him it specified GL5. and why. He was unaware of this
The GL5 has an Anti Foaming additive.

 

[Ugly Cow]

Just wondering - I get my gearbox and FD oil from a BMW independent and have simply used what was sent - Millers EP 80w90 GL4 mineral transmission oil. Now as far as I know so far its been fine but when looking in the Haynes manual I noticed it states SAE 80w90 'Hypoid gear oil API GL5'
Just wondering why a knowledgeable dealer would supply an oil not up to the spec in the manual ? I dont want to question the dealer and seem like a dumbass !!!

A hypoid crown wheel and pinion are a different design of teeth which give a greater contact area between the gears, but this design places a greater sheering force on the oil hence specific oil is required. Hypoid gear oil API GL5.

 

[Steptoe]

GL5 only. As per the bikes specifications. Simple.

 

[hughguzzi]

HMMMMM shame. 3 yrs on GL4 in gearbox and FD. Hope no damage is done, I will mention this when I get my new service bits this afternoon - and drop the bike off for some work prior to a trip to the Alps end of June ! See what they say ? I should have done my 'detective work' before asking for service bits to make sure, but you trust these highly rated places know what theyre about !!!???

The more I learn , the more I realise I didnt know !!!