Which Transmission Oil?

[suffolkpete]

I'm changing the gearbox on my 1.6, due to the usual 2nd gear synchro problems but I'm not sure which oil to fill it with.  The handbook say Shell Spirax SAE80EP but this doesn't seem to be easily obtainable.  Needless to say, Matra aren't listed in any application guides so I've tried looking up Citroen CX.  Autodata says SAE 75W/80 to API GL4.  Comma Oils suggest a 75W/90 which is API GL5.  They also do a 75W/80 which they say is specially formulated for Peugeot and Citroen, this is also GL5.  Would the Total BV 75W/80 oil used in my modern Peugeot and Citroen be suitable?  I've heard that GL5 oils can damage a transmission designed for GL4.  What do other owners use?
Peter

[Anders Dinsen]

Mine is running on Castrol driveline syntrax universal  75W/90. It has "API GL4/GL5" on the back of the can, but I don't know what the difference is.

[Oskar]

Redline MTL makes puggtransmissions as new.

try it and youll be amazed

[suffolkpete]

Redline MTL makes puggtransmissions as new.

try it and youll be amazed

Does it fix broken synchromesh?    Might save me some time in the workshop.

[Anders Dinsen]

Redline MTL makes puggtransmissions as new.

Where do you find Redline oils, Oskar?

Does it fix broken synchromesh?    Might save me some time in the workshop.

If there's still some grooving left in the syncro, it could be a temporary fix.

[Oskar]

yes
redline can fix bad syncros and stiff gearboxes

they sell it at mekonomen in sweden.

[Anders Dinsen]

they sell it at mekonomen in sweden.

I doubt if Mekonomen here in DK stocks it, but it's worth a try. Thanks

[suffolkpete]

Just spent most of the day underneath the thing.  Trailing arm bolts are rusted firmly into the bushes and the joint won't disengage from the diff.     Strange, I took the other side off a few weeks ago to change a driveshaft and it all came apart with no trouble.  This is all too much trouble for a second hand gearbox of unknown provenance.  I think I'll have to try some of that "new gearbox in a bottle" oil and practice my double declutching skills.  The gearbox can wait until there is more work needed in that area and meanwhile I think I'd better get an air hacksaw before then to cut through the bolts.

[roy4matra]

I'm changing the gearbox on my 1.6, due to the usual 2nd gear synchro problems...

Sorry Peter but no oil is going to cure that problem!  Second gear synchro failing on the CX transaxle was common owing to poorly machined 2nd gears.  Even a new synchro cone will only last a short time.  The problem is the cone hits the face of the gear before the cone faces have engaged.  There should always be clearance even when worn out.  The only solution is to change the 2nd gear and since that is no longer available on it's own, it becomes an expensive repair.  I rebuilt Anders gearbox to cure the 'missing 2nd gear synchro' problem so I know all about that one.

As for oil - a 75W/90 is fine.  I use a fully synthetic Mobil SHC 75W/90 in mine and have for many years.  It makes gear changes easy when very cold and protects well.  However, any good 75W/90 will be fine but if it is a normal (not synthetic) type then expect slow or baulky changes when cold, until the oil has warmed.

Roy

[suffolkpete]

Just as I expected.  My comment about the oil was a bit tongue in cheek.  I'm using the Castrol Syntrax oil suggested by Anders, it seems easy to obtain round here but nobody stocks Redline.  I've not seen so much swarf on a magnetic drain plug since the days when I used to drive BMC gearbox in sump cars.  Gear selection , at least on 1, 3 , 4 & 5, seems improved.  It sounds as though the spare 'box may not be any better, it came as a freebie with the car so I have no idea about its condition.  I shall just put up with it for the time being.

[Anders Dinsen]

I rebuilt Anders gearbox to cure the 'missing 2nd gear synchro' problem so I know all about that one.

But it was worth the cost! Yes, it was expensive in parts, and Roy had to search and tweak to get it right, but the result is perfect.

And with the new (correctly machined) syncro in the box, I think it can be expected to last for the rest of the car's life. During the rebuild, Roy took this photo of the old gear and syncro ring, showing how the face of the gear has been worn, even if the syncro is still more or less intact:

[roy4matra]

I rebuilt Anders gearbox to cure the 'missing 2nd gear synchro' problem so I know all about that one.

... During the rebuild, Roy took this photo of the old gear and syncro ring, showing how the face of the gear has been worn, even if the syncro is still more or less intact:

Just to clarify what that photo shows: you can see that the synchro ring still has 'teeth' where if it had been worn out it would be smooth on the inside cone face.  Yet the cone face on the gear is dull and pitted which shows that the synchro cone was not touching it at all.  It would be highly polished and shiny if the cone was rubbing it.  So although the cone was not worn it was not touching the gear - because the gear cone was undersized. i.e. machine too small in the first place!  The vertical face of the synchro cone was hitting the face of the gear before the two cones touched and the dog teeth took all the 'punishment'.  The fact that I used to double de-clutch has saved them from worse damage.

Roy

[Anders Dinsen]

Thanks for your clarification, Roy, you explain it so much better than I can
Since the rebuild, I have never had to do a double-declutch - it works like 'knife in butter'

In other words: If you have a bad 2nd and feel you have the time and resources to fix it properly, don't hesitate to take the 'box out and fit new parts. Roy got them from Citroën, but they seem to be available from Simon too.