6 Speed Gearbox Oil - GL4 or GL5? (and diff oil)

[rotorwings]

The latest caterham manual recommends EP75w90 grade GL5 oil for the gearbox, but I have found various information on the web stating that you should NOT use GL5 oil in the Caterham box. Apparently this can cause synchro problems.

Can anyone confirm or deny? Any definitive information out there?

Also the old and new manuals differ on the diff oil recommendations: So - EP80w90 GL5 or 75w90 GL4 for the diff? (BMW diff with Quaife ATB Centre)

[DCL]

The Caterham 6 is definitely GL4 only. Caterham are now fitting other boxes and that may be the reason for the change. As you say the GL5 oils damage the yellow metal parts and this includes the synchro rings.

[rotorwings]

Thanks DCL.

They should really make that clearer in their manuals.

All it says in the owners manual I have is: "Sigma/ Duratec 5 & 6 SPEED EP75w90 grade / GL5"

There is no mention of GL4 oil anywhere is the entire manual.

[viper blue]

If you look at the Caterham online parts website, and type in gearbox oil, you will see their website whilst out of stock, shows the gearbox oil to be 75W 90 GL4. This info didn't used to be shown; it changed a few days ago.

Rob

PS Diff oil is GL5.

Do not put GL5 in the gearbox; leads to issues with yellow metal parts (brass syncro wear)

[Slap_ed]

I had this very concern a few months ago and phoned Caterham South. They said that the Gearbox GL5 was a misprint, it should have read GL4, which goes with what everybody else is saying.

[downsman]

Pretty serious misprint

[forest07]

I always used Redline MTL in both my Caterham 5 & 6 speed boxes. Just about to order some from Opie Oils for the 4 speed 2000e boxes in the Elans.

TonyR

[rotorwings]

downsman said:

Pretty serious misprint

Yes!

...and I've just gone to the website to download the latest version. Guess what!? No mention of GL4, and they're still recommending GL5!

They have had the same manual up on the website since the middle of 2014 recommending GL5 for gearboxes. Amazing...