took my car for mot today...

[WestonE]

Peter

This is the issue i.e. the Sulphur content in EP5 Gear Oils attacking the Brass (in our boxes) Synchronizers. I worked for an oil company in automotive lubricants and have also stripped 20+ Beta/Monte gearboxes over the years and I have seen this sort of damage. Usually from a 75w-90 EP5 gear oil being used to improve cold shifting. I have seen a lot more damage from old oil though!

No doubt about it a good quality typically synthetic 75w 90 dramatically improves cold shifting assuming the Beta linkage is not the pile of wrecked pivots and sloppy cross links often found. So the trick is to use an oil resistant to degrading and carbonizing that gives great bearing/gear protection and likes brass. You need to read the technical spec sheet if in doubt.

Most old Beta boxes need 2 hot gear oil changes to give their best as there is nearly always a layer of chocolate brown/black carbonated oil and swarf in the bottom of the boxes from neglected oil changes and this leaves best when hot and mixed. The second change picks up the residual filth and removes it.

I have re-built more than 5 of these boxes in the last couple of years and we definitely need to get high quality clean oil in there or irreversible damage is done. I use Redline 75w 90 NS in my Montecarlo Gear Box and I have a slick change hot or cold far better than the factory change and the box is handling 190 BHP. This oil is also used by Geoff Ward in his racing Montecarlo. ZC90 (80w90 EP4) is meant to be changed every 2 years or it degrades i.e. losses the ability to be thin when cold (80w) and thick when hot (90). This makes cold shifts worse and reduces protection when hot.

Eric
Modified Monte & Beta FI Volumetrico project             

[lukasdeopalenica]

Hi guys, what about the castrol syntrans transaxle 75w-90?
I am about to use it in my reborning beta. The gearbox used to be filled by the previous owner with reddish oil that seemed to be a synthetic type.
regards

[WestonE]

Ok

I have had a look at the Datasheet and whilst not very detailed this should be fine as it is a API GL4 product not GL5 i.e. low Suplhur content.

Eric

[lukasdeopalenica]

As far as I know it has no EP additives and can be used as an alternative to GL3 oils and is marked as GL-4+.