Engine and gearbox oil

[114]

We're currently using Silkolene Silkolube 20.w50 in the engine, Castrol SAE30 engine oil in the gearbox of our Jupiter.
I'd be glad of any recommendations, given that the OEM recommendations greatly predate modern formulation oils for use in classic vehicles.
Many thanks

[David Morris]

Hi 114,

SAE 30 in the gearbox sounds fine. However, Keith Clements has delved into the best recommended oil for the engine. Apparently, the latest multi-grade oils don't suit the Javelin and Jupiter engines, due to the design of the tappet/camshaft operation.

I am sure Keith can recommend a suitable oil. I took his advice and ordered mine, as he recommended, from a company in Rye, East Sussex. Very reasonable and delivered in 25l drums at no additional cost!

All the best,

David

[114]

Thanks
After a bit of research we've used Penrite Light 20-60 in the engine and GB30 in the gearbox. Seems fine.

[Barry20383]

Am using Penrite 20_60 in my Javelin its a good solution

[Keith Clements]

I add some molybdenum disulphide (Molyslip) to the gearbox as this certainly helped during long rallies when the gearbox oil level got low after doing 500+ miles in the day. Note you should check gearbox level every 500 miles or less, if you have a drippy box. Do not overfill as it will go into clutch! There is also a breather which can get blocked (usually on assembly) that then drives oil into the clutch.

[114]

Thanks

[alexander]

Is it possible to check the gearbox breather while the box is in the car, mine does like to mark it’s patch.

[Keith Clements]

With extreme difficulty. The breather exits into the clutch housing. You could rig up a smoke generator and feed that into the filler plug and then look up into the clutch housing with the bottom cover removed. If it is blocked I doubt you can clear without separating box from clutch.
You could modify the filler plug by adding a breather. I have one on the overdrive. It is essentially a hole through the plug covered to stop ingress of water and muck. These devices are frequently used on rear axles.
On the Jup I have an extension filler pipe that can breathe.
Getting a leak free gearbox is an art which is documented in the technical notes.

[alexander]

Thanks will use spare filler plug to make a breather
Dave