On 13/08/2020 16:16, Rob Graham wrote:
On Thursday, August 13, 2020 at 9:57:21 AM UTC+1, newshound wrote:
On 13/08/2020 09:36, Andy Burns wrote:
Rob Graham wrote:

this oil "BP Energol GR 425- EP"

I can't find any mention of this oil or an equivalent

BP/Castrol say Energol oils are part of their legacy range and being
phased out, I had a nose around on their website, they seemed to suggest
Alpha SP as replacement

https://thelubricantoracle.castrol.com/range/alpha-sp/industrial/en-JP

But looks like you'll have to choose between going up, or down on the
viscosity ... maybe contact them?
In an "ordinary" industrial gearbox, one viscosity grade either way will
not matter. With a thicker oil, it will warm up a shade and drop the
viscosity. Similarly a thinner oil will run a shade cooler.

I wouldn't apply this principle to a modern military helicopter where
there may be narrower margins.

The important thing is to chose an EP lubricant so Alpha SP should be
fine. No need to stick to BP if you have another EP gear oil of the
correct viscosity.


Many thanks guys - I was assuming the '430' meant the viscosity but didn't know.
I imagine that going up to 460 wouldn't make much difference. If I went down to 320 that would make it easier for the motor but would there be a danger then of oil getting passed the shaft seals?

I would not expect so; but (given its age) if you have shaft or seal
wear you might get a bit of weeping. FWIW if it were mine I would
probably start with the thinner oil. But as I said, I'd be happy with
more or less any 320 EP gear oil. Google gives you loads. I'm guessing a
litre might be plenty, Shell Omala for £13 would be a Rolls Royce solution.