Sierra gearbox oil - pete t
Just a quick one. I'm replacing the oil in the afore mentioned box (due to most of leaking out after removing the propshaft before i could stop it) and bought some EP80 for the job. But I note from another bottle of Castrol 80/90 (not what I was going to use) lying around that it is specifically NOT recommended for use in sierra five speed boxes. I just wondered if any backroomers know of good reasons why that is so or why one should only use genuine Ford stuff. Out of interest really, I'm not sure that a 150000 mile gearbox will suffer dramatically as long as some oil is in there.
Sierra gearbox oil - John S
pete t

The Castrol bottle is right. The Sierra 5 speeds all used Castrol MTF (manual transmission fluid), and not the usual EP 80 gear oil. You may be able to buy thiis in Halfords, and not necessarily have to visit a Ford dealer.

The MTF is not unlike ATF, and much lower viscosity than EP gear oil. The risk of using the EP oil is that, when cold, the box will be very reluctant to change and will be very unpleasant to use due to the 'thickness' of the gear oil.

I've a couple of pints on the shelf you can have if you are near Swindon!

Regards

John S

Sierra gearbox oil - M.M
As John says worth keeping to spec....

But odly enough my trade guide says most of the Sierra boxes were normal 80 grade.

This MT fluid mentioned is made by loads of folks now, like Comma, and should be in all motor factors. Quite pricey but you don't need much though. Dextron II auto fluid is reckoned to be an acceptable alternative.

M.M

Sierra gearbox oil - John S
MM

Your trade guide is probably right, because I believe the 4 speeds were designed for normal gear oils - the 5 speeds were not standard on all variants until a good few years into production.

I'm basing this on my recollection of my '86 2 litre iS, when I recall having to buy some expensive MTF for top up. The shock of the cost imprinted this fact about the 5-speeds in my brain!

As you say Dexron II will probably be OK. I don't know if a Siera will be as bad as a manual RR which has EP rather than ATF in the box (I'm sure you've seen this) but if it is you wouldn't make this mistake twice!

Regards

John S
Sierra gearbox oil - Galaxy
My Ford Capri fitted with a 5 speed box used to use Castrol SMF Gear Oil. I used to buy it from Halfords. Yes, it is more expensive than EP 80/90 but, unless you have a leak, you don't need very much of it.
Sierra gearbox oil - pete t
Thank you for the replies. Armed with this knowledge actually looked it up in the application guide and, lo, something different is recommended for five speed boxes and MT75s. And thank you for the offer John S but its a bit far to go from essex even though its free!
 

Value my car