Change Gearbox Oil

From WikiLEC

The problem here is not removing oil but putting it in.

Despite beautifully clear drawings in the service notes of the Speedo cable entry/refill point, you sometimes wonder if you’re looking at the same car! Access is not easy but can be made easier by moving the coolant header tank (no need to drain) to a better position, and possibly removing the air intake hose to the throttle body.

The Speedo gear, which must be removed, is located at the rear of the differential housing and is accessed from above. Tracing the speedo cable down from the bulkhead helps locate it. A retaining plate needs to be removed by releasing a single screw before attempting removal. The speedo gear normally puts up plenty of resistance to removal so be prepared for a fight! Try not to use excessive force unless driven to it.

If you need to add or refill oil you’ll need a funnel and suitable length of hose (nobody said this was easy). The original Mobil oil specified by Lotus is no longer produced. Lotus now recommends Castrol TAF-X 75W/90, which is readily available and recommended for the S2 Elan which uses the same gearbox as the S1.

Draining the gearbox is simply a case of removing the transmission drain plug from beneath the car.

The mysterious refill plug

Some may have one. Some may not. Read on!