Gear oil life

[AdrianS]

There is no direct correlation with engine oil viscosity and gear oil viscosity. 90 gear oil is not a lot thicker than the engine oil. There is a chart somewhere online with compares the viscosities of engine and gear oils. If I can find it I'll post it

[Phil C]

Btw Paul, are you going to do some more B40 articles for The Star? I always found them very enjoyable and very useful.  Phil

[AdrianS]

Sorry, Bess had beat me to the chart!

[Phil C]

If there's not much difference in thickness, in what way is (non-EP) 90 gear oil better than engine oil?  Phil

[Bess]

Hi Phil,
           The gear oil is specifically designed for its use.
         
Engine oil additive function:

Reduce wear and friction
Stop corrosion
Cooling
Don't add to pre-ignition issues
Carry deposits, soot to the filter
Reduce emissions
Improve fuel economy
Stop ring stick
Reduce bore polish
Pre-long seal life
Don't mix with fuel
Reduce sludge
Stop foam
Stop thickening
Reduce shear

Gear oil additives

Control wear on gear teeth
Control wear on bearings
Prevent rust and corrosion
Cooling
Cleanliness
Stop foam
Not react chemically with other components

Generally gear oil is much simpler than engine oil and is usually not pressurised via a pump but splash and dip.

Best wishes...

[Dean Southall]

On several occasopns I have phoned Castrol tech dept for advice. You get through to a very helpful and knowledgable person used to old machinery. Although he has retired he enjoys helping people and admitted that the calls are redirected to hios home phone. Great stuff.

[Mike40M]

When I got a TTI gearbox for my Manx, the following was submitted:
Use Motul Gear 300 Oil 75W90 GL-5, or Castrol Syntrax 75W90 GL-5 or similar spec oil. Do not use shockproof oils.
Change oil after 5 laps, then again after 10 laps Thereafter change oil after every second race meeting.
So I simply use it in the other bikes too. According to the Motul data sheet it is friendly to all metals used in gearboxes.
There is discussions on the use of GL5 oils as some of them are not friendly to yellow metal bushings.
I think that the reason for oil changes in a gearbox is that the oil gets contaminated with small abrasive metal particles that wear produces.

[chaz]

Hi Phil,
           The gear oil is specifically designed for its use.
         
Engine oil additive function:

Reduce wear and friction
Stop corrosion
Cooling
Don't add to pre-ignition issues
Carry deposits, soot to the filter
Reduce emissions
Improve fuel economy
Stop ring stick
Reduce bore polish
Pre-long seal life
Don't mix with fuel
Reduce sludge
Stop foam
Stop thickening
Reduce shear

Gear oil additives

Control wear on gear teeth
Control wear on bearings
Prevent rust and corrosion
Cooling
Cleanliness
Stop foam
Not react chemically with other components

Generally gear oil is much simpler than engine oil and is usually not pressurised via a pump but splash and dip.

Best wishes...

Bess, you missed, oil the road, oil the rear frame parts, oil the back tyre etc
not forgetting the garage floor as well.

[Mike40M]

It's the automatic rust prevention system designed in old English bikes.

[Bess]