UN-1 DB conversion, which oil??

Title says it all really, I'm wondering what the general consensus is on the 'best' oil to use in the UN-1.

ISTR 75/90, any opinions??

Regards,
 
Julian,
When I had my box done a couple of years ago, I refilled it with Morriss’s Lodexol SS 75W/90, but any API GLI-5 Universal oil will do the job.
Tony
 
Actually after talking to the Lotus Transmission guys here in the states, of which 2 are known for their knowledge of the UN-1, and talking to them both it is agreed (independently) that GL-5 in really not what you want to use because it has a sulfur content that promotes deterioration of the synchro material and that GL-4 is preferred of which Redline MTL is the favorite of those who race Esprits. This is what Ive heard perhaps Chris Cole has a stand on this.
 
I have a stock UN1 and use Shell Transaxel oil 75W/90 syntetic GL4.
Its approve for Porsche and Ferraris Transaxel boxes.
Its with additive for LSD,but you dont need this even if you have a Quaife ATB.The Important thing is to use a oil that is suposed to be used in this type gearbox because of the crownwheel/pinion and syncrorings.
A pure GL5 oil is ment for higeloaded crownwheel and pinion in a rear diff,but not intended to use in a gearbox with syncrorings (because of the wear described in this tread).
 
I believe in Europe the oil to use is Mobil SHC630 (or something around there)! and here in NZ the similar equivalent is Castrol Syntrax 75/90.
 
Thanks for all the replies. Following on from the information posted & a bit more internet surfing, I opted for Castrol TAF-X 75/90 which seems to be the best available.

Looks like 'gear oil' is very different to 'diff oil' which is different again to 'transaxle oil'.

Regards,
 

Andy Green

Supporter
Good choice Julian, as this is what was the factory fill oil on the Lotus Esprit which used basically the same transmission.

Regards
Andy
 
Hi Julian

You asked which was the 'best' oil for the UN1 - in my opinion the best oil is Fuchs Silkolene Silktran Syn 5. This has excellent properties to lubricate the gear box and also being fully synthetic, meets the requirements of the Quaiffe ATB differential. I have used this for over a year now and can report excellent gear change and quiet running. Only one downside, it is over £10 per litre, but the best is never cheap!

Best wishes.

John
(just finished restoring an E type that I first raced myself in Modsports over 35 years ago!)
 
Andy,

I'm a big fan of Lotus engineering, so it's good to hear that!

John, I'm sorry to say the Castrol is nearly £16 per litre!!! Will bear in mind the Silkolene product for future reference, thx for the info.

Regards,
 

Howard Jones

Supporter
I have tried 75W90 Redline, 75W90NS Redline and 75W140NS Redline. The 75W90 didn't like the synchros and the shifting seamed to take a lot more rev matching. Especially between 1st and 2nd on the upshift. I changed to the 75W90NS and the shifting got better. Enough for me to recommend it over the 75W90. The NS leaves out the limmited slip friction modifiers.

I have since gone to the 75W140NS, mostly because of the track time my car sees in the heat of California summers.

I have a Chris Cole main shaft with the closer 1st and 2nd gears along with a Quaife ATB diff in my UN-1. The final ratio is 3.44 and engine power is about 300HP at the wheels.

Redline oils webpage below

Red Line Oil: Gear Lubricants
 
Planning to replace the oil in my UN-1 (long overdue) and rereading this thread I noticed it is about 12 years old so wanted to check if the current thinking had changed. I gather Castrol TAF-X 75/90 hasn't been available for some time so would assume 75W90NS Redline would be one possibility but note that its to GL-5 specs and from above discussion there is some preference for using GL4 spec. Any input from the forum would be welcome.
 

Eddy McClements

Supporter
Planning to replace the oil in my UN-1 (long overdue) and rereading this thread I noticed it is about 12 years old so wanted to check if the current thinking had changed. I gather Castrol TAF-X 75/90 hasn't been available for some time so would assume 75W90NS Redline would be one possibility but note that its to GL-5 specs and from above discussion there is some preference for using GL4 spec. Any input from the forum would be welcome.
Hi Trevor

The obsolete X has been replaced by...


Castrol Syntrans *Transaxle 75w/90 synthetic

The "which oil" thread has been done to death over on the Lotus Esprit forums, and the oils originally spec'd by Renault and Lotus have disappeared from sale (Mobil SHC 630M and Castrol TAF-X). It's worth bearing in mind:-

Oils spec'd by Renault / Lotus were based on what was available at the time, and this was before the general availability of synthetic oils.
Oil standards have been changed, and some additives are banned owing to being subsequently identified as hazardous to health.
The replacement oils, had they been available at the time to Renault / Lotus, would in all likelihood have been approved, but as they had yet to be developed they never made it onto the "approved list"!
The UN1 is a transaxle, not just a gearbox. The oil needs to handle the heavy load between crownwheel & pinion, as well as the movement of gears, bearings & synchros, and shift rods. The need for a heavier oil to protect CWP can mean a less-than ideal shift quality.

*Note: there is also a Castrol Syntrans Multi-vehicle 75w/90 which is Not the Same Thing.

But...other members also report good results from Redline and Millers products.
 
Hi Eddy,
Thanks for the info. As you point out, Castrol Syntrans looks like preferred choice from the Esprit forum. I checked out on-line to see if anyone this side of the pond (Canada) sells it and found Amazon.ca price was $62CDN for 1/2 litre!! At 3.5L to refill the box that would work out as the world's most expensive oil change! On the link you sent me a more reasonable price of £17/L is quoted, but shipping costs are likely to be in the £45-50 range. A lot cheaper than Amazon but likely over $200 + import duty for an oil change still seems a bit steep. It's probably not an area to cut corners, but before I decide, just wondering if people using Redline and Millers products are still happy and with no issues?? If I understand correctly 75W90NS Redline would be one option.
 

Eddy McClements

Supporter
Do you have a limited-slip-differential, and if so, which type? There's a Redline Synth 75W-90NS GL5 for non-LSD applications - part #58304. Can't remember the Millers recommendation last time this came up...maybe CRX 75W90? Someone will chime in shortly.
 
No just the std diff. I figured I'd carry on with it until there was an issue with the box (leaking seals, or whatever) that required opening up the box, then think about the one piece input shaft and ATB diff. I work on the basis of let sleeping dogs lie, or if it ain't broke don't fix it.
 
Hi Trevor, Nice to see this thread bought alive again!
I still own the car & it is still fitted with the same UN-1, with Derek Bell's upgraded input shaft & a Quaife ATB diff.
I've been using Castrol Syntrans 75W-90 for more years than I can remember & transaxle is in good order. I change the oil every year when the car is used on track.

I usually buy from Opie Oils; https://www.opieoils.co.uk/p-6363-castrol-syntrans-transaxle-75w-90-fully-synthetic-car-gearbox-oil-formerly-taf-x.aspx

Hope this helps,
Kind regards
Julian
 
Yes it does thanks, Julian. From the info that's been provided here, I've decided to go the Castrol Syntrans 75W-90 route. It works out about $100CDN more expensive than the most likely alternative but all things considered, that's not really an issue. I'm sure the alternatives described here are completely ok to use too.
 
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