Gearbox oil choice?

[craig chima]

Hello,

I'm curious about recommendations for gear oil choice for close ratio synchro gearbox. Application is actually a Turner Mk III with 1500 Ford and 3 rail box with straight cut CR gearset. Virtually all my experience over the past 35+ years has been with dog boxes and we can get away with extremely lightweight synthetic oils in these boxes but have very limited experience with synchro boxes in racing applications and wondering about the appropriate weight to use and thoughts on synthetic vs conventional.

Thanks in advance for your thoughts.

Craig Chima
CC Motorsports
Akron,OH,USA

[rgh0]

I have used Redline MTL for many years in my Elan box in racing with the straight cut syncro Quaife gearset

cheers
Rohan

[craig chima]

Rohan,

Thanks for the prompt reply. I've used MTL in a lot of dog box applications with good luck but didn't know if it was appropriate for synchro box.

Craig

[gjz30075]

Craig, as long as it's GL4 only. That protects the brass synchros.

[Donels]

I put MTL in my Elise synchro box. The difference was night and day. A recalcitrant gear change was transformed and the whining at 60mph almost eliminated.

[craig chima]

Perfect, thanks!

[Baggy2]

Not sure if I'm breaching forum etiquette here but as the heading is gearbox oil choice I'd like to ask the same question about the Lotus 5 speed box - road use only.
Ive seen Redline MTL recommended before on the forum but what caused me to ask was the specific mention above that it reduced whine. I have only had my 5 speed box in for a few months and it whines more than I expected.
Collective wisdom and experience would be very wecome.
Thanks
Baggy

[mbell]

I run my 5 speed on redline, currently mt90. Also used redline mtl previously. It works well. I switched to mt90 as had a weak/gone 4th gear synchro and hoped it might improved that.

I've replaced the synchro now and still running the redline mt90 as that's what I had on the shelf.

Can't speak to it for racing but also switched the daily driver with getrag 420 box on to redline mt90. Was a significant improvement to the shift action on the gearbox.

[jono]

I put MTL in my Elise synchro box. The difference was night and day. A recalcitrant gear change was transformed and the whining at 60mph almost eliminated.

That's interesting as my S2 111S Elise, K engined, is pretty noisy/chattery and I was looking for a suggested replacement oil for the box to see if it improves. I will give that a go.

[Baggy2]

Thank you Jono . The people who installed the gearbox used TAF-X. Think I'll replace it with MT90
Cheers
Baggy