gearbox oil AG 90

[DaveTomo]

At the moment using rock oil st90 in my gearbox,but for me to get it this time of year,no runs or parts fairs, and no local stockists after reading this http://www.messerschmittclub.org/karoscene/?q=node/706 (similar to a lammy ,wet clutch etc) would this be suitable? http://www.tfmsuperstore.co.uk/index.ph ... ct_id=1274 ,I'm just thinking if I'm going to have to send off for it might as well get a 5 litre container .Any ideas?

[soosh]

As long as its ok for wet clutches,it should be fine. I've never seen st90 stocked anywhere near me and for years just used a medium gearbox oil,its usually Silkolene.

[purple_pill67]

I got localish motoX place (that I used to deliver to) who stocks Rock Oil to order me some in.
Think theres a few places in Gloucester that stock Rock Oil too if I need some again.

[Andy Pickering]

my eldest sons work use tons of rock oil hydraulic oil so i get a few freebies from time to time as the rep is an old scooter boy and was even sent a rock oil jacket last xmas

Sent from my GT-I9000 using Tapatalk

[dirtyhandslopez]

Here you are, try this: http://www.morrislubricants.co.uk/scrip ... Product=16.
I have been using it for years. Our local Brit Bike Club Rep is a dealer.

[tom-wsp]

Here you are, try this: http://www.morrislubricants.co.uk/scrip ... Product=16.
I have been using it for years. Our local Brit Bike Club Rep is a dealer.

Plus one, morris oil is the shizzit.

[Muttley McLadd]

shizzit.

You're the second welsh person I've seen use that word today.

What does it mean?

[hydra]

ST90 is a straight SAE 90 monograde gear oil and is available from several manufacturers. But, contrary to the Lambretta manual and other publications, you don't now have to stick with this basic oil. Gear oils are rated with a GL number from GL1 to GL6, SAE 90 is a GL1 oil and as such as no EP additives. As the GL number raises, so do the amounts of EP chemicals added to the base oil to protect the gears, with hypoid gears needing the most protection. These additives have now moved on since Lambretta's were in production in the 60's, when the EP chemical pack included additives that attacked yellow metals and silver bearings, I am running a TS1 on Maxima MTL 85, which is a GL3 Oil and as such has mild EP additives with no problems at all and offers a lot more protection from wear than a GL1 oil. The other myth surrounding EP additives is that it causes Clutch slip, this is totally untrue, this back in the day was probably caused by friction modifiers, the such of which is used in car engine oil. I have also used a 10W/40 Bike engine oil with success as this as no friction modifiers and as such is used with wet clutches. Believe it or not a 10W/40 engine oil is the same viscosity approximately as SAE 90 gear oil, the reason the numbers are different is because of the different temperatures the two oils are tested at. The thing to look for in bike oils is the Jaso spec MA or the later MA2, which is the spec test for wet clutches.
Hope this helps and doesn't bore you to death.

[DaveTomo]

Cheers chaps,I think I'll give it go

[dirtyhandslopez]

ST90 is a straight SAE 90 monograde gear oil and is available from several manufacturers. But, contrary to the Lambretta manual and other publications, you don't now have to stick with this basic oil. Gear oils are rated with a GL number from GL1 to GL6, SAE 90 is a GL1 oil and as such as no EP additives. As the GL number raises, so do the amounts of EP chemicals added to the base oil to protect the gears, with hypoid gears needing the most protection. These additives have now moved on since Lambretta's were in production in the 60's, when the EP chemical pack included additives that attacked yellow metals and silver bearings, I am running a TS1 on Maxima MTL 85, which is a GL3 Oil and as such has mild EP additives with no problems at all and offers a lot more protection from wear than a GL1 oil. The other myth surrounding EP additives is that it causes Clutch slip, this is totally untrue, this back in the day was probably caused by friction modifiers, the such of which is used in car engine oil. I have also used a 10W/40 Bike engine oil with success as this as no friction modifiers and as such is used with wet clutches. Believe it or not a 10W/40 engine oil is the same viscosity approximately as SAE 90 gear oil, the reason the numbers are different is because of the different temperatures the two oils are tested at. The thing to look for in bike oils is the Jaso spec MA or the later MA2, which is the spec test for wet clutches.
Hope this helps and doesn't bore you to death.

While you are on that roll mate, Spectro 60w Harley engine oil works as well. As does straight 30 non detergent engine oil. Lots of things work.
90w definately keeps the chain noises down though As I am sure you are aware, and I may be wrong on this, but a 10/40 oil is a 10w when cold and a 40w when hot, so you are going to be hearing some rattles when it warms up.
Beside that, if you give people too many options, you get that deer in the headlight look from them so it is a whole lot easier to just go with what was origianlly specified for the Lammy gearbox IMO.