Manual Transmission-Gearbox Oil-Fluid Synthetic Options?

[n_tensetuning]

Hey guys

Understanding that factory manual calls for:
MIL-L-2105C or GL5
Above-20°C (-4°F) SAE 80
Below- 20°C (-4°F) SAE 75

and understanding the requirement for GL-5 Hypoid Gear oils for our (Manual) transmissions...

Trying to see what our options are for (Synthetic Gear Oils): (examples)

*Royal Purple Max Gear Synthetic *** for use of an API GL-5 or GL-4 fluid. Formulated with hypoid friction modifiers necessary for use in clutch or cone type differentials.
https://royalpurpledirect.com/max-ge...etic-gear-oil/

*75W-90 Mobil 1 Synthetic Gear Lubricant*

*Red Line 57905 75W90 GL-5 Gear Oil*

*Fuchs TITAN GEAR SYN 75W-90 Semi Synthetic Driveline Oil. Rated as gl4 / gl5.*

*Liqui Moly GL-5 75w-90 for API GL5MIL-L 2105 C , MIL-L 2105 D
https://products.liqui-moly.com/full...-75w-90-2.html


Curious how many others have had success with (FULL SYNTHETIC) gear oils in our (Manual) transmissions.

Thanks
Dave M

[Ron]

I wouldn't go heaver than ##W80, whatever you use.

[MikeWard]

I wouldn't go heaver than ##W80, whatever you use.

Why not? Just curious as I've run Castrol TAF-X 75w90 fully synthetic in mine since mid 2012, 8 years on and 20k+ miles later and haven't had any ill effects from using it.

[Ron]

Why not? Just curious as I've run Castrol TAF-X 75w90 fully synthetic in mine since mid 2012, 8 years on and 20k+ miles later and haven't had any ill effects from using it.

The spec calls for SAE 80W for above -4°F. Besides rarely getting that cold in ATL, when the engine gets warm, the multiblends listed would be 90W. A bit Too heavy...

I haven't used it personally in a D, but FWIW- 75w80 GL5 (HERE):
"Performance level
API GL-5
MIL-L-2105 B/C/D
Recommended for use:
...
Peugeot
Renault"

[dn010]

What are you trying to achieve by using synthetic? Here is a good thread regarding the oil with Dave Swingle saying they've had the best luck with conventional. At nearly 40 years old, everything has wear - FWIW, I found the best way to get smooth, crisp shifting was not by the oil, but by replacing all components of the shift linkage, crossgate cable and then adjusting everything to spec.

http://dmctalk.org/showthread.php?542

[vwdmc16]

Said it before but I love Redline MTL, I've had a few cars delorean and not that would grind gears and shift poorly until MTL went in and transformed it. I don't know what magic they have in that bottle, but it has worked many times for me.

[David T]

The Delorean seems to be OK with ordinary mineral based lubricants in the transaxle, that is what it was designed for. It isn't overloaded and doesn't need anything exotic. In fact, it works so well that there is little if anything to be gained by using a synthetic. Not the case in the Lotus but in that application the Renault transaxle is dealing with a LOT more power. Unless you are abusing the car, you should be fine with regular hypoid gear oil.

[MikeWard]

The spec calls for SAE 80W for above -4°F. Besides rarely getting that cold in ATL, when the engine gets warm, the multiblends listed would be 90W. A bit Too heavy...

I haven't used it personally in a D, but FWIW- 75w80 GL5 (HERE):
"Performance level
API GL-5
MIL-L-2105 B/C/D
Recommended for use:
...
Peugeot
Renault"

Fair enough.

I was going from the Lotus recommended spec for the UN1 gearbox, which is 75w90 GL-5 fully synthetic. It works well for me.

Side note Castrol TAF-X has long since been discontinued (it was hard to get hold of when I bought it back in 2012), a recommendation from GTO Racing for a replacement oil is Millers TRX Synth 75w90: https://www.ebay.com/itm/322853880714

[n_tensetuning]

Thanks everyone for your input.

Came across this link
https://www.thelotusforums.com/forum...taf-x-no-more/

Looks like the Lotus boys are using
* Castrol Syntrans Transaxle 75W-90 (Formerly TAF-X 75w-90) synthetic Transmission Fluid *****new Oil specified for the Esprit Renault UN1 Transaxle
*Redline MT90
*Millers CRX 75w-90 NT
*Castrol Manual Syntrax 75w-90 Full Synthetic


other useful links:
http://freudhoefer.de/lotus/esprit/p...e/oils/oil.htm

http://www.lotusespritworld.com/EGui...ssion_oil.html

[n_tensetuning]

Spoke to Techs @ Royal Purple and confirmed for our Delorean DMC-12 V6 manual transaxle,
Royal Purple Max Gear 75W-90 (part #01300, quart bottle) is exactly what they recommend.

Max Gear: http://www.royalpurple.com/product/max_gear/

Max Gear already includes the limited slip differential friction modifier.


D