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Gearbox oil? TAF-X No more?


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Hi again,

I don't pretend to understand these numbers, perhaps someone can explain.

From what I can find on the internet these are the specifications of each oil -

TAF-X

SAE 75w/90

Density 0.860 @ 20 degrees C

Viscosity ( mm2/s) 73 @ 40 degrees C

Viscosity 14.4 @ 100 Degrees C

Visc Index 210

Flash Point 220

Pour Point -45

Millers TRX

75w/90

0.867 @ 15 Degrees C

98.8 @ 40 Degrees C

14.2 @ 100 Degrees C

147

200

-48

And the Millers is specified as 'Fully Synthetic' ?

Regards, Phil.

Edited by philip600
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Or just buy the TAF-X.

Millers TRX 75W-90 is semi-synthetic whilst the TAF-X is fully synthetic. There is a fully synthetic version of theTRX.

The two TRX oils have a much lower viscosity index than the TAF-X which means they are not as capable of maintaining their viscosity over a range of temperatures.

TAF-X is 75W90

TRX is 75W90

How is that thinner?

From a random google surf...

"The less change a motor oil has from high to low temperatures gives it a high Viscosity Index. Synthetic motor oils that are made from Group IV (4) PAO base stocks have Viscosity Indexes of more than 150 because they are manufactured to be a lubricant and don't have the paraffin that causes the thickening as they cool. But petroleum based motor oils (Group I (1) & II (2)) usually have Viscosity Indexes of less than 140 because they tend to thicken more at the colder temperature due to the paraffin despite the addition of Viscosity Improving additives. The higher the Viscosity Index number the less thinning and thickening the motor oil has. In other words, high number good, low number bad. Low numbers thicken more as they cool and thin more hot. You see these Viscosity Index ratings posted on data sheets of motor oils provided by the manufacturer."

The article was about motor oil, not transaxle oil, but you get the idea.

Being second is to be the first of the ones who lose.

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Wow thanks for the explanation - but now I'm confused....

I always thought the 75W90 was the measure of the viscosity at 2 fixed points: xxW/yy (xx being cold and yy hot)

So 2 oils with the same 'weight' can have different viscosities? Or is that because at 15* and 100* they are around the same viscosity but at 40* they are not?

I suppose that the gearbox oil doesn't get *that* hot under normal driving so maybe that is the important bit?

If you managed to get both oils to 100* they are pretty much identical - no?

Lotus Esprit S4 - Work in progress

Porsche 924 Turbo - Parts chaser

Smart Roadster Coupe - Hers

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From a knowledgable source:

Castrol TAF-X is currently the Specified Lubricant for the Lotus Renault UN1 Transmission.

TAF-X is still available from Lotus Aftersales and Castrol still has stock.

Castrol has advised Lotus that TAF-X 75W-90 is no longer being manufactured.

Their replacement is Castrol Syntrans Transaxle 75W-90

This is a Fully Synthetic Gear Oil.

The Oil Temperature generated in the Lotus UN1 Transmission can reach Temperatures of 150 Deg. C.

The currently specified Castrol TAF-X (and the originally specified Mobil 630M) were capable of operating in this range.

The replacement proposed by Castrol (Syntrans Transaxle 75W-90) is currently being evaluated by Lotus.

From the technical specification we expect this product to be suitable for use in the Lotus Esprit UN1 Transaxle.

We will advise the outcome of the testing.

Many other products may be suitable for use in the UN1 Transaxle.

We would advise owners to be cautious on selecting an alternative product.

We have seen Transaxles returned to Lotus as part of an exchange scheme where the gearbox internals had suffered severe wear or failure.

The investigation into the failure sometimes revealed that an unknown lubricant had been used. This may have contributed to the failure of the gearbox.

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Interesting that the hot oil weight is at 100*C so at 150* who knows what different oils will do.

If TAF-X and TRX are different viscosities at 40* I imagine that they are very different at 150*

Thanks for clearing that up.

Rich

Lotus Esprit S4 - Work in progress

Porsche 924 Turbo - Parts chaser

Smart Roadster Coupe - Hers

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Its nice to know that Lotus are still testing suitable products for a vehicle which went out of production 10years ago and also that they seem to have some kind of exchange scheme for broken gearboxes!!

Excellent!!

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"We have seen Transaxles returned to Lotus as part of an exchange scheme where the gearbox internals had suffered severe wear or failure."

This is exactly why I have adopted the technique of driving in neutral whenever possible. By keeping the gears disengaged whenever underway, wear and tear on the assembly is substantially reduced, and has the added benefit of a significant decrease in required engine RPM. However, I have noticed when employing this technique that the car seems to slow down appreciably, and often requires reselection of an appropriate gear to get back up to speed. I've also experienced a notable increase in horn honking activity by following traffic, and numerous single digit salutes from passing vehicles. Still, I'm firmly convinced that the use of this approach to long term transaxle usage will ensure an exceptionally long life for the unit, almost as effectively as leaving the car parked in the garage.

Being second is to be the first of the ones who lose.

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Still, I'm firmly convinced that the use of this approach to long term transaxle usage will ensure an exceptionally long life for the unit, almost as effectively as leaving the car parked in the garage.

I take it you wear the obligatory hat while driving at all times (neutral or not), indicate right whenever you approach roundabouts (no matter which exit you're intending to take), tow your caravan (you wouldn't want to leave it at home in case it's stolen) & frequently stop to refill your pipe with 'Old Shag' before having a good old puff. thumbup.gif

Cheers,

John W

http://jonwatkins.co.uk

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Most important of all always stop at a roundabout.

Even if there is no traffic for hundreds of miles (Other than the semi-permanent queue behind!) you must come to a complete stop, handbrake on, neutral, top up pipe, adjust pork pie hat, smooth string backed gloves then look and proceed on your way normally and in perfect safety.

Lotus Esprit S4 - Work in progress

Porsche 924 Turbo - Parts chaser

Smart Roadster Coupe - Hers

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" almost as effectively as leaving the car parked in the garage.

Its alright for you John-my car doesn't even live in a garage!!

Do you know if this will negate my Lotus warranty??

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FYI - I'm using Castrol Syntrax (F/S) 75W-90. I'm sure it's the Aust Castrol version of the Syntrans.

Simon  (94 S4)      My Esprit will be for sale in late 2017

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Its alright for you John-my car doesn't even live in a garage!!

Do you know if this will negate my Lotus warranty??

Hi Nick.

I have it on good authority that sans-garage parking will not negate the Lotus warranty, as long as you don't open the tailgate and remove the luggage tray for longer than 27 minutes. Exceeding that limit kicks in the pro rata "sliding scale" warranty reduction clause, somewhat like a battery warranty. If it's shown that it was raining at the time of exposure, a 15% additional reduction in warranty coverage applies. Driving the car whilst in such configuration completely voids the transaxle warranty, as well as tailgate strut(s) coverage if forward speed exceeds 100 mph.

Cheers,

John

Being second is to be the first of the ones who lose.

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Ahhh-i see!

Well up to this point in time i think i should be ok as i don't recall having left the tailgate open for that length of time in wet weather nor driving forwards at 100mph-surely that would be highly illegal in any event and also possibly result in death or serious injury- SPEED KILLS!! (I know this to be true from a "knowledgable source")

However this does give me somewhat of a dilemma as i have just fully loaded my luggage compartment with what i can only hope will be a lifetimes supply (that's my lifetime-not the car's!) of Castrol Syntrans Syntrax TAF-X TRX GL4\GL5 75w-90 gear oil that i was intending using in my transaxle in order to maintain the warranty BUT it is due to rain this weekend!

What am i to do?? Risk opening the tailgate for too long in the rain OR leave the "wrong" oil in my gearbox for even longer??

Any suggestions would be greatly appreciated as im fresh out of ideas myself!!

Thanks guys

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No problem, Nick. I recommend you seek shelter under the nearest Motorway flyover and perform any gearbox oil changes whilst thus protected. Be sure to make a photographic record, complete with date and time stamps, as Lotus can be quite finicky about their warranty interpetations. Unless the rain is wind driven at or above 30 mph, or exceeds a 37.5 degree angle from vertical (whichever occurs first), I believe your warranty coverage remains in full force. Hope this helps.

John

p.s., with your described cargo of a "lifetime's supply" of gear lube in the luggage compartment, I suggest a minimum of 50 psi in the rear tyres for optimum handling.

Being second is to be the first of the ones who lose.

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Thanks for your suggestions John(Heath)-im currently organising a trailer to take my car to the nearest motorway as i fear driving it there with the wrong gear oil would undoubtedly negate the warranty completely!!

I appreciate your suggestion re increasing the rear tyre pressures BUT are you serious-500psi?? FIVE HUNDRED-really??You think i should inflate them to FIVE HUNDRED pounds per square inch-that's 500psi?? Surely they would explode at that kind of pressure?!!!

Ahhh-sorry i misread-50psi! That's more like it! This will give me a chance to use my brand new digital tyre pressure guage i received as a Christmas gift-i've been longing for an excuse to use it since!

That said i do hope it goes up to 50psi-if not i suppose i could get them to say 30psi then add another say 20psi shortly afterwards?

Thanks again for all your advice-i don't know what i would've done otherwise!

Nick

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Nick, If you're really that concerned about driving the car to the nearest flyover with the wrong gear oil, may I suggest that you simply remove the transaxle in its entirety first, and use a hire car to transport it to the motorway. You can then perform the oil change there, return the unit to your home, and reinstall it. Just be sure you complete the R&R in under the specified 27 minutes to avoid the pro rata warranty decrease, and I think you'll be good to go.

Cheers

John

Being second is to be the first of the ones who lose.

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You've got me all worried now.

I checked my gearbox oil ( didn't need any topping up after all that ! ) but I didn't do any of the above, I just crawled under the car whilst in my garage & checked the level, will this have voided my warranty ?

Yours, very concerned, Phil.

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Not meaning to be rude, Phil, but you've not gotten back to me on how the Millers tastes on cereal. This information will be going into the data base as an important facet in the decision making process of gear lube choices.

However, I'm willing to let this "slight" pass for the moment. You'll recall that NIck's concern was his lack of a garage to begin with, and what effect that might have on the Lotus warranty. I've provided the "work around" details (as I understand them) in previous posts. In your case, as you in fact have a garage (and are quite obviously part of the "landed gentry"), and performed your maintenance procedure within the protective confines of said structure, you've no cause for concern. Your warranty is still good, and be thankful for it.

Best,

John

Being second is to be the first of the ones who lose.

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Phil- i am a little concerned for you and have some questions:-

How exactly did you "check your gearbox oil" and how do you know it "didn't need any topping up after all" - as you so casually just say as if its that straight forward?

What i am wondering is how you know what specific oil is already in there and what you were considering using for the top up had you needed some?

I mean- what if it has Castrol in there now (as im sure it must have for warranty continuity) and you were going to top it up with Millers? Do you realsie that all kinds of hell could've been unleashed ??

It seems you may have got away with a lucky escape on this occasion but in future may i suggest you take things a little more seriously than just -as you say- crawling under your car whilst in your garage!

Regards Nick

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Not meaning to be rude, Phil, but you've not gotten back to me on how the Millers tastes on cereal. This information will be going into the data base as an important facet in the decision making process of gear lube choices.

However, I'm willing to let this "slight" pass for the moment. You'll recall that NIck's concern was his lack of a garage to begin with, and what effect that might have on the Lotus warranty. I've provided the "work around" details (as I understand them) in previous posts. In your case, as you in fact have a garage (and are quite obviously part of the "landed gentry"), and performed your maintenance procedure within the protective confines of said structure, you've no cause for concern. Your warranty is still good, and be thankful for it.

Best,

John

I didn't realise how complicated this would become !

I'm sorry to anyone awaiting my feedback on how the millers oil tastes on cereal.

To make ammends I have, on this very cold & frosty morning walked to the shop, yes WALKED ! ( I don't want to jepordise my warranty by using the Lotus ) & I purchased some cereal. You didn't specify which type so I bought cornflakes, shredded wheat, cocoa pops & some all bran.

I than walked home & performed a very scientific experiment to see what the millers tasted like on each cereal.

I weighed out 25 grams of each cereal into four ceramic bowls &then poured on 100ml of said oil, my finding where as follows -

Cornflakes - Tasted ok but very chewy.

Shredded Wheat - These where very nice.

Cocoa Pops - Mmmm, didn't like these as they didn't turn the oil chocolaty as stated in the advert, very mis-leading.

All Bran - These were the best, the oil completely masked to hideous taste of the cereal !

I hope this information is useful for your survey ?

With regards to the garage, I must point out that whilst performing this work, although the Lotus is fully within the confines of said garage, I need to have the door open to allow me to access the rear of the car. This means my legs are outside the perimeter of the building, is this ok or will I need, in future the crawl along form the front of the car to allow the doors to remain closed.

It must be said I didn't have any of thses problems with my previous Porsche warranty !

Yours ever hopefull, Phil.

Phil- i am a little concerned for you and have some questions:-

How exactly did you "check your gearbox oil" and how do you know it "didn't need any topping up after all" - as you so casually just say as if its that straight forward?

What i am wondering is how you know what specific oil is already in there and what you were considering using for the top up had you needed some?

I mean- what if it has Castrol in there now (as im sure it must have for warranty continuity) and you were going to top it up with Millers? Do you realsie that all kinds of hell could've been unleashed ??

It seems you may have got away with a lucky escape on this occasion but in future may i suggest you take things a little more seriously than just -as you say- crawling under your car whilst in your garage!

Regards Nick

Hi Nick,

You are of course correct, it wasn't just a matter of 'crawling under the car'

In the interests of saving time I did shorten the event somewhat, so to make ammends -

On Thursday 12the January at 6.12pm I entered the garage where said Lotus Esprit is stored.

I had to open the door ( please see post above ) to allow access for me to get under the rear of the car to find the gearbox oil level plug. I could not find this so out came the handbook to find picture of plug location. Back under car with light, but still couldn't find it ! Crawled back out & again checked the picture in the handbook, realised I was looking on the wrong side & crawled back under.

Found the filler plug ( passenger side, not drivers, unless of course you have the steering on the wrong side in which case drivers side )

Took out 10mm chrome vanadium open ended spanner & attempted to loosen said plug, Mmmm, a little tight.

Bit more force needed......snap ! One broken spanner. rant.gif

Crawled back out from under car ( again ) & searched for another spanner, eventually found one in BMW tool kit.

Back under car with WD40 & after 20 minutes of swearing, cursing & grazing my knuckles the plug was loose smile.png

Slowly removed plug until it was free from gearbox at which point oil was seen to be draining from the hole so the plug was immediatley screwed back in & tightened ( I supose this should have been torqued to correct tightness but by now I was pretty bloody sick & my neck hurt & my knuckles were sore ! )

I maybe should have quickly topped up to allow for amount of oil that had drained out ?

Crawled out from beneath the car put tools away, closed the door & exited the garage at 8.10pm.

With regards to how I know what oil is in the gearbox, I can only go on the invoice form last year when the oil was replaced by a Lotus specialist & is listed as Trans-X. Other than this I have now idea.

I hope this ammends my previous articles short comings & will be of help to someone performing this job in the future.

Good Luck.

Regards, Phil.thumbup.gif

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Phil

Just one more slight concern has arisen regarding your much more detailed explanation:-

I really hope you confirmed that WD40 is an approved Lotus lubricant as once again this may invalidate your warranty!!

On a brighter note i think you may have a possible warranty claim for your broken spanner as you appear to have followed the recommended procedure to the letter-they're quite good like that at Lotus what with their lifetime unlimited warranties!

Porsche on the other hand-well i've heard their warranty isn't worth the paper its written on! 3years or 36000miles Haha! Pathetic!!!

Finally-great work on the cereal testing! I think the post should be pinned for ALL members to digest at their own leisure

Well done

Nick

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Phil,

May I extend my appreciation for your submission of the results of your gear oil taste tests. These findings will be entered into the Gear Oil Overall Experimental Yield, or GOOEY, data base for future referrence by interested owners seeking the best solution to their transaxle lubrication requirements. While there may be multiple products available to meet these needs, I feel that it is always good practise to select one with good taste, so to speak.

Regarding the need to have your garage door open for access to your vehicle, I think it is safe to say that having one's legs extending "outside the perimeter of the building" will not void your Lotus warranty. However, for any owners who might have had certain medical procedures performed, such as hip replacements and the like, it would be prudent of them to investigate the "fine print" of their policy to ascertain any environmental limitations imposed by the manufacturer of such devices. I'm fairly confident that Lotus, accomodating as they might be, would not likely cover ancillary damages of this nature. Incidentally, if you are indeed capable of reaching the drain plug by "crawling along from the front of the car," may I suggest you apply for a spot appearance on Britain's Got Talent at your earliest opportunity. I, for one, would be exceptionally interested in observing this feat of derring-do.

In closing, may I state for the record that I have seldom seen such an exquisite transition from what began as a serious inquiry, morph into a segue of such complete, yet subtle, fabrication with admirable finesse by all concerned. My uncontrollable mirth brought on by the readings of this saga created howls of such magnitude as to draw the attention of my spouse, who entered the room in a state of rapt inquisitiveness as to the source of such Homeric laughter, whereupon I treated her to selected portions of the unfolding story, thereby reducing her, also, to a state of convulsive amusement.

Steady on, gents....cheers.gif

John

Edited by Iconic Ride

Being second is to be the first of the ones who lose.

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John, you seem to be suggesting in your last paragraph that I am not taking this subject seriously, I can asure you this could not be further from the truth ! To prove this point I will be carrying out further testing once I am well ( I seem to be suffering from chronic indegestion at the moment, must be something I ate ?doc.gif ) using TAF-X & Syntrans oil on the same cereals to ensure the testing is fair & subjective.

I have also decided in order to be completely scientific I am going to try using various types of milk ( full cream, semi skimmed & skimmed ) in the gearbox of my S4s to assertain the lubicating qualities & longevity & also to ensure once the worlds oil supplies have been exhausted we can still run & enjoy our Lotus cars driving.gif

On the point of access from the front of the car, you are correct in that it would be difficult to say the least. I have however calculated that if I install new springs that are + 150mm this will allow me, with the help of some petroleum jelly to 'slither' to the rear of the car, I will look further into this at a later date. This will also have the added advantage that entering & exiting the Esprit will be much easier.

Nick, I will look further into whether WD40 is a recognized lubricant by Lotus & approved as such, I will report back my findings.

I am also going to submit a claim to Lotus for the cost of the aforementioned damaged spanner.

Your's respectfully, Phil.

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