Diff Oil ??? EP or not EP ?

[Ron Hayhurst]

There's plenty to read about on this topic in the above search box. I have used a suitable EP oil for over fifty years with none of the troubles some would suggest. As "recently" as 1950, in the Official Austin Publication For Light Cars, Ref 2230, there is a list of the many companies supplying lubricants and it states that a 140 EP rear axle oil is required for all Austins from The Seven through to The Fourteen. Shell Spirax 140 EP is just one of them. If there was a problem with sulphur attack or any other serious effect It would have been noted long ago and changes made to this recommended lubricant. I have yet to see a component that has suffered "attack". Let's here from those who have.
Ron

[Tony Griffiths]

Just avoid a teaspoonful of 3 in 1.

[Graham Barker]

There must be a story behind your comment about 3 in 1. Are you going to enlighten us?

[David Stepney]

There appears to have been much discussion over the years about the suitability (or otherwise) of oils in Austin Sevens. What seems to have passed owners by is the fact that motor oils have improved incomparably in the last 90 or so years since our cars were first built and their lubricating properties have increased beyond all recognition. They are all rather more slippery, can withstand greater bearing pressures and are more stable than hitherto.

Given that our cars do comparatively few miles each year (Mine is considered well used at about 5K miles per annum) I would suspect that choice of lubricant is rather a matter of personal opinion. For instance, my car runs on a good quality 10W/40 semi-synthetic motor oil for the engine and gearbox and a good quality straight SAE140 for the steering box and rear axle. The car has now done 113K miles in its life. The engine has its original crank and bearings and is still running on a rebore to 20 thou that was probably done in the fifties or early sixties. So far as I am aware, neither the gearbox nor the back axle have been overhauled during its life and make no worrying noises. The gearbox whines like a banshee in second, but don't they all(?) and the rear axle hums, but, Heigh Ho, the car is nearly ninety years old and is as reliable as Old Nick.

It is, however, regularly serviced, The engine oil level is checked every time it goes out, and the chassis points are greased and the gearbox, steering box and rear axle levels checked every 1250 miles. It is my opinion, therefore, that, provided the oils used are suitable for the application using the spirit of the recommendations in the handbook and the levels are maintained, all will be well and choice of lubricants will be purely a matter of preference.

[Reckless Rat]

You can certainly cause problems by overfilling the rear axle, and it's important when servicing that the axle is hanging on the springs to avoid overfilling. On the D type axle you really don't need any more than 250ml (1/2 pint) or it will endeavour to find its way out by either the half shaft seals, contaminating the brakes or (if you have a special with lowered suspension) via the torque tube.

140 grade oil is quite viscous when cold but fluid when hot. Notwithstanding, if you paint the springs with it, it will drip (don't ask me how I know that)

[David Stepney]

You can certainly cause problems by overfilling the rear axle, and it's important when servicing that the axle is hanging on the springs to avoid overfilling. On the D type axle you really don't need any more than 250ml (1/2 pint) or it will endeavour to find its way out by either the half shaft seals, contaminating the brakes or (if you have a special with lowered suspension) via the torque tube.

140 grade oil is quite viscous when cold but fluid when hot. Notwithstanding, if you paint the springs with it, it will drip (don't ask me how I know that)

Exactly so, Bruce.

I usually warm my SAE140 oil can up in a saucepan of boiling water. It makes it much easier to replenish the axle (with the car suitably supported with axle stands under the chassis)

[Tony Griffiths]

There must be a story behind your comment about 3 in 1. Are you going to enlighten us?

It might - or might not - be a Colin Chapman quip when asked how to reduce oil drag in the back axle. Early axles were filled with a glutinous mixture of grease and oil - hence the sealing arrangements to prevent this from escaping down the axle tubes and contaminating the brakes were either rudimentary on nonexistent. It's ages since I had an axle apart - what were the sealing arrangements of the later screw-in and long flange types?

[Steve Jones]

Barry Clarke sometimes used ATF in both the gearbox and rear axle when sprinting and hillclimbing. Much too thin for use when going any distance but for short runs on the track, it was good enough - and very, very thin!!

Steve

[Colin Wilks]

I was talking to a chap with a racer at the centenary. One of his tips was to drill the underside of the axle near the hub so that oil which would otherwise spoil the brake linings dripped onto the road instead. Anybody else done this?

[Hedd_Jones]

I discussed this with a friendly oil geek some time ago.

His opinion was that a vintage car running a factory engine and not towing was unlikely to get EP oil hot enough in a bevel axle where it would attack yellow metal. His conclusion was therefore it mattered not a jot what oil you use, EP or not. 

I use compounded 460 bearing oil. Same as I use in the bearings of my steamers.