BUT WHICH ONE’S THE RIGHT ONE? GRANT FORD

Grant is left scratching his head when it comes to choosing the best oil for his Jag’s gearbox and rear axle

1965 JAGUAR Mk2

No doubt there are plenty of CCW readers out there who will correct my choices when exploring the world of classic car oils, but it’s easy to make a mistake when you’re faced with an assortment of internet opinions that often failed to compare with my Sixties workshop manual.

It has been almost a decade and nine thousand miles since my last assault on the fluids within my Mk2’s gearbox and rear axle – long enough to forget what a chore it is without a ramp. But armed with a one-litre plastic bottle plus a tube and plenty of enthusiasm, the old Jag was up on stands with drain plugs removed in little more than 20 minutes.

I thought that my research would pay dividends and the manual suggested 30 weight oil for a non-overdrive Moss ‘box with a mere 1.5 litres required. The internet is full of suggestions for alternatives but they are dependent on temperature and primarily discuss use in engines and not gearboxes. I decided to play safe, stuck with the manual and found that Uk-based Smith & Allan supplies a non-detergent mineral SAE 30 listed ‘vintage car’ delivered at £20 for five litres. The differential prefers a bath in EP90 hypoid – is that better than 80W/90? If so, why do some companies supply both? Add on the confusion of GL4 or GL5 – and can they be mixed? – and all this means that lube decisions can give your average classic enthusiast a serious migraine.

Again, my fear of getting it wrong guaranteed that I followed the manual and wasted nearly an hour trying to squeeze hypoid in from below. Restricted access ensured that there was no assistance from gravity so a re-fill was required once half a litre had left the container – an easy garage task with the right tools, a ramp and transfer pump but I am too tight for their

labour rates. Many advise the warming technique by placing a full container in boiling water but past misdemeanours surrounding this sort of thing mean that anything garage-related is strictly banned from the Ford kitchen.

I used the ‘fill it until it overflows’ method in both cases – the rear axle guzzled more than the 1.3 litres suggested but the gearbox consumption was exactly as the manual predicted. A packet of kitchen roll was the only other expense, mostly used to clean up the garage floor, and a small road test confirmed that there were no apparent leaks from either area.

Next task is the steering box, which can only be topped up from above and the correct fluid according to Jaguar is GP90/140, another option that requires investigation. It seems that there is only one lube fact that I can report conclusively – namely that SAE 30 is much easier to wash from my thinning hair than used hypoid…

RIGHT: Steering box with filler bolt pointed out courtesy of a long screwdriver. Yet another viscosity required, plus a longer hose. Wedging the bottle alongside the handbrake cable means no access to squeeze out the EP90 that delights our diff’.

Moss’ box with drain plug removed. With limited access to the filler a mess is pretty much guaranteed.

Using a torch to highlight metallic content confirms why regular fluid changes are essential for the rear axle.