stupid question

[southenddc]

i know this is gonna sound stupid to you guys but im a complete novice, so please humour me..

Is differential oil, the oil we use in the gearbox?

cheers

[Skerd]

Do not put the same oil in the engine and the transmission!

[kmaier]

Mid-engined cars use transaxles, which simply put has the transmission and differential in a common case. This creates a bit of a problem as most differentials require a hypoid gearlube as there is extreme pressure between the ring and pinion gears. Transmissions on the other hand usually avoid hypoid gearlubes as they are too thick and, in the past, have had additives which are corrosive to the copper-based alloys used for synchronizers (brass).

Gearlube specifications are GL-x ratings, ie, GL-1, GL-4, GL-5, etc. which have specific uses. The Renault transaxle (UN-1) which is in the current Esprit is spec'd for a GL-4 gearlube due to the fact the GL-5 gearlube is a hypoid rated gearlube (hence the additives). While the UN-1 does have a hypoid final gear drive, it also has brass synchronizers so one must be careful on the gearlube used. As a result, gearlube used in the (UN-1) transaxle is a compromised choice.

Now for the good news.... many of the newer GL-5 rated gearlubes still use sulphur-based additives known as EP (Extreme Pressure) but are "inactive compounds" while older GL-5 gearlubes used "active compounds" which are corrosive to copper and it's alloys (brass in the case of synchronizers). I recently switched over to Mobil-1 Synthetic gearlube which has a GL-5 rating but is NOT corrosive. Lotus Cars USA also recommends this for the Esprit and the dealers use this by default when servicing the Esprit.

There has been much debate about this on the turboesprit list (yahoo groups) and you will find that many Esprit owners swear by the Redline MT-90 (a GL-4 gearlube) but with the extreme heat in South Florida I went with the Mobil-1 gearlube. If you have some free time, I would suggest you browse the TE list as there is some good reading amongst the strong opinions. Hope this helps....

Regards, KM
2000 V8

PS - the Mobil-1 website has much detail on their products and worth some reading.

[southenddc]

Please forgive my naivity....i have differential gear oil GL5...is this ok to put in the geabox?

[dr.hess]

Well, as he said, there is a lot of debate on the gear oil issue. The net result was that it is best to use Redline MT-90 or the one that the shop manual (service notes) says is the _only_ one to use, which is Mobil SHC-630, available a Graingers Supply, and _nothing else_. So, if you have something labeled "differential oil," while it may not hurt your box, it is probably not the best thing to use. It may not hurt your box, buy why risk it?

Dr.Hess

[southenddc]

ok nice one folks, i appreciate your help.thanks

[kmaier]

I have had some correspondence with Derek Bell in the UK who uses the UN-1 for racing and has an exceptional upgrade kit for it (on my list) and he told me he would not use the Redline MT-90 in the Renault box.... and I respect his opinion. He also recommended the Mobil SHC1 gearlube. Below is a link for the Mobil-1 Gearlube which I can easily buy at any local parts store and is what I am currently using, as well as what LCU and the dealers are using.

www.mobil.com/USA-English/Lubes/PDS/GLXXENPVLMOMobil1SyntheticGearLubricant.asp

Good reading and has the best of both worlds... GL-5 rating for the Hypoid final drive and non-corrosive additives which will protect the synchronizers and various bushings, etc., ie, anything based on copper alloys like brass. The data sheet also recommends it for applications which specify a GL-4 gearlube. Overall I think the box shifts every bit as good, if not better, than when I used the MT-90. Then again, I am once again experiencing serious gearbox problems again (on the new box) so it would appear I have a different problem, most likely a clutch issue or an alignment problem :-(

So, rather than use the GL-5 gearlube you have... as it appears to be an unknown, I would just recommend you buy known product and use that just to be safe.

Regards, KM
2000 V8

[dr.hess]

And here is the one the manual says to use:
[url]www.mobil.com/USA-English/Lubes/PDS/GLXXENINDMOMobilSHC600Series.asp[/url]

Available at:

[url]www.grainger.com/[/url]

Just changed mine about fifteen minutes ago with the SHC 630.

Dr.Hess

[southenddc]

I appreciate the links and the help guys, ive actually got the citreon box (UK 86 S3). Ill check out the Mobil as my best option then..

cheers again

Brett

[dr.hess]

Well, the 88-92 Service Notes on the Citroen box don't specify the SHC 630 as the Renault box notes do. Actually they say:

"refill ONLY WITH MOBIL SHC 630M,"

for the Renault box, verbatum, including the all caps which is why everyone freaks out when it comes to the discussion of what oil to use. The Citroen box section does not specify the 630 only. BTW, Mobil dropped the "M", so 630 is the same as 630M.

OK, the service notes say that for a 88 (Citroen box) to use "API GL5 SAE 80" gear oil, so if the stuff you have meets that requirement, you are OK.

Dr.Hess

[cnh1990]

I know of only one person who has used just about all available tranny fluids that would work in our cars.
(Mark Wiens from the SFO area of California).

He has logged the different results on the turbo list and we had much discussions on this subject. Mark and I used to chat quite a bit because of the similar work both of us has done on our cars. Personally I think he had taken the tranny fluid change to an extreme. But the info was really helpfull to many.

I think in a space of several months he must have changed it 3-4 times. But then again he did perform a valuable service in logging the changes he observed. If you send me your email I will forward to it to Mark and I'm sure he will fwd the results of his observations.
Calvin

[lotusguy]

cnh1990 said:

I know of only one person who has used just about all available tranny fluids that would work in our cars. (Mark Wiens from the SFO area of California). He has logged the different results on the turbo list and we had much discussions on this subject. Mark and I used to chat quite a bit because of the similar work both of us has done on our cars. Personally I think he had taken the tranny fluid change to an extreme. But the info was really helpfull to many. I think in a space of several months he must have changed it 3-4 times. But then again he did perform a valuable service in logging the changes he observed. If you send me your email I will forward to it to Mark and I'm sure he will fwd the results of his observations. Calvin

Calvin,

You should note that Mark just recently blew-up his tranny. Cause & Effect??...Jim'85TE

[cnh1990]

A bearing went out. I don't think the changes in itself had much to do. He had put some miles on the car in a robust manner, so it's not too different from some of the other transmissions that we have seen rebuilt. A lot of people have used the fluids Mark has had with ill effect. I have a tendency to go with Keen and just use the original stuff.

Calvin

[Mark91SE]

[quote]
Calvin,
You should note that Mark just recently blew-up his tranny. Cause & Effect??...Jim'85TE
[/quote]

Now Jim... be nice. As it turned out, the tranny was on its way out, which is why it was making noise in the first place. The Pinion shaft bearing was going bad for a long time... just getting louder. Its failing was not due to changes of lube, but undoubtedly failed sooner due to my adding a hi-torque chip and testing it full boost often. None of the 3 lubes I tried really made much a difference for that noise. Now I have a Sport300 tranny in there w/LSD and only 4,000 miles on it. I did decide to stay with the Mobile SHC630 in it, but am tempted to replace 1 Qt of the 3 in there with MT-90. Redline said it can be mixed okay with other synthetics. I will grant you this... after all the experiments, I will say I can't really recommend one over the other. My shifting is just fine with the SHC630 though, and I haven't ground second once yet... heh. It might loosen a tad with MT-90 in there, but we'll see. I'm not anxious to crawl under there too much anymore.

Mark91SE

[paul c]

Brett,
Thought you had sold. Does this mean you've got another Esprit? That was quick!