Although Castrol EPX 80W/90 gives adequate protection, I have found that Castrol Hypoy LS-140 gives better protection to the diff than EPX and most of the racing fraternity here use it in their track cars. With the increased torque available from C engines now, I feel it is good practice to use LSC-140 especially if towing or driving through mountain passes. Castrol Hypoy LSC-140 is specially formulated heavy duty gear lubricant of SAE 85W/140 viscosity, meeting MIL-L-2105C and the now superseded API classification GL6. The product contains friction modifiers and is recommended for limited slip differentials when an SAE 85W/140 viscosity is required or where greater protection is required than can be offered by API GL5 gear oil.

As for the gearbox, I use either Castrol EP 90 or Valvoline 85W/90 in preference to engine oil as this gives a better gear change and will make the lay shaft and 1st motion shaft needle rollers last almost indefinitely. I got the clue from the oil recommendation for the MGB GTV8 as the gears and their bronze bearings are exactly the same as the C, only slightly closer ratios. I did 30,000 miles with my CGT with no deterioration of the gearbox.

Under NO CIRCUMSTANCES use Castrol Syntrax in a MGA, B, or C gearbox. It is too slippery and the baulk rings are unable to grip properly on the gear cones with expensive results!! Crunched gears and broken baulk rings.

Working forward on the car to the engine I have settled on using Valvoline Syngard 15W/50 which is a semi-synthetic oil. I feel a semi-synthetic is essential in the C engine as most of the oil drains out of the oil filter canister over night and it takes a few vital seconds for the oil pressure to build up on starting. Therefore, an oil that clings to surfaces is a must. Here in New Zealand most semi-synthetic engine oils are 10W/40 for use in modern cars and Valvoline is the only oil company that markets a 15W/50 semi-synthetic engine oil "brewed up in Australia at a reasonable price" To unnecessarily use a full-synthetic soon empties the pockets with the huge sump capacity of the C.

I hope these few remarks learnt over a period of more than 15 years with M.G.s may be of interest to Register members.

Dave Romer