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Discussion Starter #1
I know this is an eternal question, but does anybody have a source for Shell Dentax 90 gear oil, or does anybody have some they can sell me for my 2000 gearbox?

Thanks,
Stu
 

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Push hard and live
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Stu,

I bought a 35 pound pail from some outfit in California. Just Google Dentax and look around. I don't recall the name of the shop, but they keep it in stock.

Meanwhile, in another thread R Jemison is telling us that Redline NS is a better lubricant for our early boxes. I may drain my Dentax and try some later this year, although my box is working OK on the Dentax. Normal 2nd gear, and occasional pop out of reverse, but nothing that bothers me.

So - you might try the NS.
 

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But Mad North-Northwest
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Well, Dentax 90 is non-EP GL1. Redline 75W90NS is an EP GL5. So I'm not sure I'd try that.

If they're near you, Napa Auto Parts carries their own brand of GL1 which will probably work fine. Click link below for the part number and info.

NAPA AUTO PARTS
 

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Push hard and live
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Tom,

I can't speak to the details that were presented in the other forum, but I had the impression that the NS is NOT a GL5 spec, and and is specifically formulated as a non EP oil as required by our early transmissions and the later limited-slip difs. You might go search the other thread.
 

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Discussion Starter #5
Don,

I've googled and googled for Dentax 90 but cannot find a domestic source. Seems that it's available in Malaysia and Australia though... Can I buy some of yours?

Regards,
Stu
 

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Push hard and live
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Here you go... http://www.theindustriallubricantstore.com/shell-oil-dentax-s-50-oil-replacement-5-gallon

I don't have any to spare, as I've already given some away and need to keep what I've got to service the 102. Sorry.

There are probably other sources for Dentax, but this is the first one that popped up via a google search.

BTW, I think the SAE 50 is a motor oil viscosity spec that is similar to the 90W gear oil spec. I'm not all that clear on that point.
 

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But Mad North-Northwest
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I can't speak to the details that were presented in the other forum, but I had the impression that the NS is NOT a GL5 spec, and and is specifically formulated as a non EP oil as required by our early transmissions and the later limited-slip difs. You might go search the other thread.
Redline 75w90NS is most definitely EP and GL5. The only difference in the NS is that it doesn't have the LSD friction modifier additives. It's all on the Redline info page:

Red Line Synthetic Oil - Gear Oil for Manual Transmissions - 75W90 NS GL-5 Gear Oil

Mongo dunno, it may work okay. But it's not GL1.
 

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Push hard and live
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Tom,

Like I said, this is not really my area of expertise. RJ provided his opinion in the other thread, which came across as well-tested. I was taught to use Dentax about 40 years ago, and so bought a big pail of it. RJ seems to think that the NS without the friction modifiers works great in the old gearboxes, and it is, of course, much easier to obtain. The reasons I was originally given for using Dentax was that the later oils were too slippery, and so the synchros didn't work right, leading to wear on the gears and other components crashing into each other. If the reduction in friction modifiers has addressed that (which the Redline website discusses), it may well be a great alternative. I'll get around to trying it at some point, but I'm too busy right now.
 

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But Mad North-Northwest
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I've googled and googled for Dentax 90 but cannot find a domestic source. Seems that it's available in Malaysia and Australia though... Can I buy some of yours?
Stu: there's a Napa Auto in Sandpoint. Give them P/N "NHF 65205" and they can order you a 5-gallon bucket of Napa branded GL1.

It's not Dentax brand but it's the exact same spec: GL1 90wt mineral gear oil with no additives. The GL1 90wt spec is the key part: it should work absolutely fine.
 

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dentax

As far as I know, Dentax is just Shell's GL-1 non-EP gear oil. GL-1 is used widely in trucks and other heavy equipment. I went to our local distributor with the Dentax specs, and he had the Chevron equivalent in 5 gallon cans. He called a local truck service station for me, and they helpfully pumped a gallon of their stock into my one gallon can. It worked fine in my 101 Giulia and 1750 GTV transmissions.

I don't understand the mysticism about Dentax.

Barry
 

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Interesting. The 1750 came after the switch to EP style oils
 

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Dentax - mineral vs synthetic

Hi all,

I have followed this discussion a few times on the Alfa BB (e.g. http://www.alfabb.com/bb/forums/1900-2000-2600-1950-1968/78616-2000-touring-need-change-gearbox-lubricant.html), and the whole Dentax 90 issue remains a mystery to me.

I understand that Shell Dentax 90 was one of the two recommended oils for the transmission, AGIP Gambi e Differentiale SAE90 being the other according to the plate under the hood.

According to the product sheet, Shell Dentax 90 is now called Shell Spirax S1 G 90 (http://lugolfo.com.mx/Spirax S1 G.pdf), which is a GL1 SAE 90 mineral oil. The specifications for that oil (e.g. wrt viscosity) are very different from the synthetic Shell Dentax S 50 Don refers to. Also Shell Dentax 80W90 (now called Shell Spirax S1 G 80W-90, http://www.epc.shell.com/Docs/GPCDOC_GTDS_Shell_Spirax_S1_G_80W-90_(en)_TDS_v1.pdf), mentioned in a previous thread, has very different specifications from Shell Dentax 90 (e.g. it is GL-3 instead of GL-1).

So, why would these oils be a better replacement than any other oil with 'similar' specifications than the original Shell Dentax 90?

By the way, according to the shell product catalogue (http://www.epc.shell.com), Shell Spirax S1 G 90 is still available in the USA (but not in the EU?)

Gr., Pieter
 

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I have Dentax in the 64, I will try the Redline N S in the future, just did a oil change. All OK.
Who is currently using what in their early box, and give comment.
 

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The link I provided to the Dentax 50 was hastily done, and probably doesn't contribute to the discussion. However, I just checked my pail, and it is labeled "Dentax 80W-90, GL-1 gear oil".

So, Pieter's post may or may not be correct regarding the 80W-90 now being a GL-3 lubricant. I bought this pail about 3 years ago from an oil distributor that I found online, I think in Socal. It would take hours to find the receipt (although I have every receipt for this car's restoration).

In any case, it tells us that, in recent memory, a Dentax GL-1 was available in the US via mail order. It wasn't all that expensive for what will probably turn out to be a lifetime's supply, particularly if I try the NS and it proves to be superior.
 

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Push hard and live
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Here is the place I found my Dentax 80W-90, GL1. They no longer list it, although they have a variety of "Spirax" products. It might be worth sending along an email and see what they say. As I recall, it was listed online, and I bought it via a click and "pay now". Easy.

I'm guessing they would get it, or the new Spirax equivalent, upon request. They gave me good service.

I just sent a query to them to see what they say.

F&L Petroleum Products
 

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Richard Jemison
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What??

I`m amazed that you guys would even consider using a 50 year old lubricant!
It screwed up the syncros then and I suspect you think it won`t now!
Brilliant thinking!

The defination of insanity is doing the same thing repeatedly and expecting a different result!
 

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Looks like Don and I are the only folks still with D but will use RL NS next change. In hindsight over all the yrs I'll admit the gbox has been the weakest part of the car.
 

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RJ,

It has little to do with repeating a known mistake. I was taught - with some severity - that Dentax 90 was the only thing to use with the older Alfa transmissions. Barring any new information, that's what I've used. Your relatively recent post in another thread is the first time I've heard there might be a better alternative.

So - wouldn't insanity require that there was a known or apparent alternative? This is the first I've heard about it. One does not know what one does not know.
 
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