Gearbox Oil for the Traction Avant

[David FaulknerParticipant]

In Floating Power Jan/Feb 2018 there is a Technical Article on the Traction Avant Gearbox with some links to Gearbox oil. There has been conflicting advice out there for some time as to what oil is safe to use and I thought I would try and get some clarification for everyone so I e mailed the Technical Departments at Miller Oils and Castrol  quoting the recommended oils in a 1952 Citroen Traction Avant owner manual from the Technical Document Section on site:

My Query: I own a 1952 Citroen Traction Avant and have a query on which gearbox oil to use.
The gearbox and differential share the same oil, the drive being transferred via a crown wheel and pinion in the differential to the front wheels.

Now the gearbox is a 1930’s design which never changed until the car was discontinued in the mid 1950’s and does contain some phosphor bronze bushing the wear of which seems to allow 2nd gear to run out of alignment causing a disastrous failure of the gearbox (which I would like to try and avoid!).

Various sources say that because of the yellow metal bushes a modern EP oil should be avoided and as far as can be ascertained the original specification was for an SAE 90 oil

So who is correct and what oil should be used in the gearbox please?

The resulting replies follow:

Miller Oils:

For this Citroen I would recommend our Classic Gear Oil EP 80w90 GL4,

We do not do a straight EP 90 GL4 so we would offer the multigrade, which has a larger operating range which leads to increased protection when the gearbox is cold.

Modern gear oils do not contain active sulphur anymore – the chemical that used to attack yellow metals. Modern advances in chemistry and formulations allow EP oils to be used in older applications were yellow metals are present.

Castrol:

The current and correct lubes for your Citroen are listed below.

Engine: Castrol Classic XL30

G/Box/Diff: Castrol Classic EP90 (API GL4)

So from the above there are at least 2 modern options available here in the UK. For anyone further afield I would assume that as an alternative any modern oil that meets the current API GL4 specification could also be suitable (but do check with the supplier)

[Martin de LittleParticipant]

In reply to David’s note above…..

Miller it seems produces two  kinds of oil for elderly gearboxes.  There is their “Classic Gear Oil” (which is a GL4 type) that David mentions and which was recommended by Miller. Then there is their  “Green Gear Oil”   (aka “Vintage Green Gear Oil” which is a GL1 type).

Below examples from the Millers web site of cars that might use their Vintage oils.  All rather confusing. As a guide,  the advice seems to be, use a GL1 type of gear oil.

 

MdeL

[David FaulknerParticipant]

Have a read of this https://www.millersoils.fr/en/the-various-different-types-of-gear-oil-confuse-me-what-does-gl1-gl4-and-gl5-etc-mean/ from Miller Oils which may help clarify the position.

Remember that the Traction Gearbox has synchromesh on 2 of the forward gears AND the oil is shared with the differential so it gets quite complex in choosing the correct oil but all sources I have found are quite clear that anything with GL5 specification should be avoided in classic cars.

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