Later BTR are technically spec'ed to last 30,000-50,000 miles with a fluid change (I change mine every 10,000 miles). The level should be checked at every service however (every 3000-5000 miles).

WATCHPOINT for BTR LSDs (Limited slip differentials);

We have had extensive correspondence with both the Australian manufacturers of the axle and the Morgan/BTR specialists in the UK.. The ONLY recommended lubricant for a BTR LSD is Castrol SAF-XJ. This lubricant is easily sourced in the UK and Europe but is not available in North America and many other countries. However, a BTR was used by BMW in one of their models at it can be sourced under their part number at any BMW dealer. Buy 2 litres. This product already contains the necessary "Friction Modifier".

Should you read or hear of any advice of ANY other lubricant for these axles, ignore it and sue the writer. In all the years of BTR use, the only failures  heard of is from people who ignored this rule. The first sign of failure will be a clicks or light clunk with attitude changes. Damage will commence as soon as the wrong lubricant is used and will progress at a rate depending on what was wrongly chosen.

To replace, take the car (if possible) on a short run to warm the lubricant a bit.

1. Place the car on a level surface.

2. Jack up the rear and remove the level plug.

[A BTR has only two plugs, one is at the bottom rear and often ignored by the uninitiated as they mistake it for a rear cover bolt). It is used to drain the lubricant. The other is a threaded plug a bit offset to the right in the middle of the rear cover. This one acts as a filler and level indicator.]

3. Remove the drain plug. (As a precaution, you can strain the lubricant to see if any debris is present.)

4. Replace the drain plug.

5. Using a container or funnel/tube that allows access to the rear filler hole, fill the differential until the lubricant runs out of the filler hole.

7. Replace the filler plug.

8. Clean the differential and check for leakage at both plugs after your first run.

BMW and BTR recommend that the fluid level be confirmed regularly but it need only be changed every 50,000 miles.

Filling a SALISBURY LSD Axle (Plus 8s)
by Lorne Goldman

The recommended oil for a Salisbury LSD is a 80/90 Hypoy oil for limited slip differential (LSD) axles.

To replace, take the car (if possible) on a short run to warm the lubricant a bit.

1. Place the car on a level surface.

2. Jack up the rear and remove the bottom plug of the differential and allow the lubricant to drain. (As a precaution, you can strain the fluid to see if any debris is present.)

3. Replace the bottom plug.

4. Remove the filler plug located at the rear right of the differential.

5. Remove the plug at the top of the differential.

6. Fill from the top until the lubricant leaks from the rear hole

7. Replace both plugs.

GREASING A MORGAN PROPSHAFT (4/4s, Plus 4s, Plus 8s and Roadsters)
by Lorne Goldman

The Morgan propshaft has not changed much in 50 years...at some point the splined end of the longer section changed from metal to neoprene but little else of note was altered. From time to time, if it is out for a period for another reason, it is could be wise to have it tested for balance, as an unbalanced propshaft will cause vibration.

Sadly, though it requires very little care, it often doesn't get ANY! It needs to be greased and have come across many they haven't been seen a grease gun a decade and more after they left the Factory.

The propshaft has three grease points. One within the rear u-joint that it is bolted to the axle, a second at the front on the body of the propshaft that fills the propshaft itself and a third on the second u-joint at the front of the propshaft that is bolt to the output shaft of the gearbox.

The rear grease point is accessible from underneath or above  the axle compartment. Raise the rear of the car and turn the rear wheels until you see the grease nipple and you have a good line on it for your greaser. The front two grease points are accessible from underneath the car or from an access panel at the right or left at the rear of the gearbox cover. The access panel will vary in placement or sometimes not exist at all!