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Synthetic Gearbox Oil for The Manual Transmission


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Recently, I have been doing some reading (I can't call it research :blush: ) on the viability of using fully synthetic gearbox oil in the Z's 6-Speed Manual Transmission. There are some 'wild-assed' statements on the US forums (as usual) about "you must use this and don't use that" etc.

 

The standard OEM gearbox fluid and LSD fluid is taken from this thread http://www.350z-uk.com/forum/viewtopic.php?t=399 i.e.

 

Transmission, manual, 6 speed Manual

Capacity: 2.9 liter

Gears forward: 6

Gears reverse: 1

Use: normal - OEM recommendation

year-round API: GL-4 SAE 75W-85

 

Differential, front, limited slip Capacity: 1.4 liter

Use: normal - OEM recommendation

year-round API: GL-5 LS SAE 80W-90

Use only limited slip hypoid gear oil which is approved for Nissan LSD.

 

Guy (oilman - www.opieoils.co.uk) has kindly provided some detailed information on this subject and note in particular my question to him was posed in the context of the GL-4 and GL-5 ratings identified above.

 

Please do not take this as a recommendation from 350z-uk to change or 'upgrade' your gearbox oil, merely as additional technical information from an informed source in the industry.

 

From oilman,

 

This is what the GL specs mean;

 

API designation Operating conditions Engine manufacturer approval

GL-1 Rust and oxidation preventive, non-EP-effect lubricant without additives. Very few fields of use, mainly for light load helical serration transmissions and drive shafts. Volvo

 

GL-2 Transmission oil with a higher additive level than the previous, without EP effect. For medium load vehicle worm drives. For use in a very limited range of European equipment.

 

GL-3 Lubricant with light EP effect for transmissions and non-hypoid gear drives. Used by several vehicle manufacturers for first fill of transmissions. Fiat

 

GL-4 Medium EP effect lubricant for synchromesh transmissions and moderate load hypoid gear drives. The most widely used specification. Most vehicle manufacturers specify this performance level. Mercedes-Benz 235.1

MAN 341

VW 501.50

ZF TE-ML-02

 

GL-5 High EP effect lubricant for hypoid gear drives, rear axles, differentials exposed to heavy loads and transmissions exposed to shock loads. Not always suitable for lubrication points requiring a lower performance level. Mercedes-Benz 235

MAN 342

ZF TE-ML-05

 

With a growth in popularity of the various disk-type, oil lubricated, limited slip differential locks, the demand arose for a new lubricant feature, mainly in the API GL-5 performance class: the requirement for limited friction coefficient, so-called LS (limited slip) transmission oils. Here the limited lower-value-friction coefficient of the lubricant assures the torque transfer between multiplate disks and thus the partial locking effect of the differential. This specialised capability can be ensured through the use of special additives designated by the abbreviation LS. The use of other transmission oils where this type of oil is required could result in serious malfunctions.

 

In short the GL4 is to do with Syncro (yellow metal) and the GL5 is loadbearing/friction.

 

You cannot use a stright GL5 oil in the gearbox, you can however use a GL4/5 as these are very good GL4 gear oils that are so tough they meet the extreme pressure requirements for hypoid applications such as diffs and lsds.

 

For the 350z the 75w-80 is a mineral option, the 75w-90 will be fully or semi synthetic and either a GL4 or a GL4/5 is fine.

 

The quality option is for a GL4/5 75w-90 such as the Motul Gear300 75w-90, there will be no warranty issues as the oil exceeds the specs called for by Nissan.

 

Also, Guy reviewed a number of threads I sent him from my350z.com and made the following comment in particular

 

Gear oils, in the main are quite easy things to understand (most gearboxes actually take the same stuff), the trouble is so many.. over analyze.

 

Interesting I noted many US users were using the Redline gear oil, for all their analyzing they failed to find out why it quietens down transmission, this is because it has a very large amount of Limestone dust within it, great inital results as people notice a change (this is what they are looking for) but in the long term does not do any good what so ever.

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Everything above is correct but Amsoil gear oils are and have been stunning for 30 + years and is how I discovered the product in the first place.

In the '80's I needed a gear oil to keep a standard Jaguar gearbox alive behind a 650BHP V12 for drag and track racing I was worried but after finding Amsoil at a show I found I needn't have been. The only damage the gearbox had in over 4 years of racing was a bent selector caused by my brute force and red mist. Years later on acquiring my Jaguar Le Mans car I was in the same situation with a similar amount of power going through a Hewland gearbox rated at 400BHP. Asking around I found that the trick was once again Amsoil as it was being used by much of the Can Am car owners to keep the regulated standard boxes together with V8 Chevy engines pumping out upto 1000BHP. I found the very same dealer again and got some Amsoil gear oil. Never had a problem in this department and later found out that Group 44 who ran the car in the States (where it won the Miami GP) used Amsoil in it in those days!

Amsoil has also gone to F! teams who should remain nameless, but as 1 of the teams has been sold I am sure Eddie wouldn't mind.

Basically I am trying to explain that Amsoil gear oils are a tried and tested product.

As is explained above GL4 for the 'box and GL5 for the diff. In Amsoil terms this is:-

MTG 75w-90 GL4 for the gearbox

SVG 75w-90 GL5 for the diff.

 

http://www.performanceoilsltd.co.uk/gear_oils.html

 

or of course buy it from Opie Oils

 

To give you an idea of the quality SVG is good for upto 500,000 miles in lorry differentials! so the 360Z should be mighty fine with it.

 

As for value for money Amsoil MTG is cheaper than Motul 300 and the SVG is more expensive but.... and I stand to be corrected here, the Motul 300 is not a LSD diff oil as Motul do a dedicated LSD diff oil. It could be used with the addition of additives which would add to the cost and aggravation in putting it in and no doubt making the Amsoil SVG cheaper and easier to use.

 

As for Redline for whom Performance Oils used to be dealers..... I have just a little bit left for customers who really insist on it; we will not be ordering more. To quote their ex top salesman the gearbox oils 'have issues' I have a 5L pot of Redline that has been standing for a considerable time and it has creamy deposits settled out at the bottom to a height of a couple of inches which more than tends to support whats been said! Might add a pic if anyone is really interested but just best stick to Amsoil or Motul!

Enough said.

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  • 3 years later...

Mobil 1 Synthetic Gear Lubricant LS is a supreme performance, synthetic, multi-purpose, SAE 75W-90 automotive gear lubricant designed to meet the highest level performance requirements of modern passenger vehicles in all types of operating conditions including limited slip applications, as well as, deliver outstanding power transfer performance. Compared to conventional hypoid gear lubricants, Mobil 1 Synthetic Gear Lubricants LS 75W-90 performs exceptionally over a wide range of temperatures. Mobil 1 Synthetic Gear Lubricant LS 75W-90 achieves this through a unique proprietary formulation, that deliver optimized viscosity-temperature properties together with the highest level of inherent formulation stability and protects against thermal and oxidative degradation, wear and corrosion, viscosity loss associated with premature shearing. It also can be used in extended service and for aiding in fuel economy performance.

 

Mobil 1 Synthetic Gear Lubricant LS 75W-90 meets the most severe API Service MT-1 and GL-5 EP gear oil service classification.

 

 

Features and Benefits

 

Mobil 1 Synthetic Gear Lubricant LS 75W-90 combines wax-free synthesized hydrocarbon base oils and a specially designed extreme-pressure, limited-slip, sulfur-phosphorous additive system to provide a significantly higher level of performance in rear axles and differentials versus conventional fluids. Greater film strength at higher operating temperatures, reduced fluid friction and low-temperature application down to -50ºC provides significant advantages versus conventional mineral oil formulations. It reduces wear and spalling under the high speed, high torque and high horsepower conditions in competitive racing and high performance automobiles. This unique, high technology final drive gear lubricant has demonstrated outstanding performance including; fuel economy, extended drain, long-term friction retention, low-temperature capability and improved differential/axle durability and cleanliness.

 

Applications

 

* Mobil 1 Synthetic Gear Lubricant LS 75W-90 is recommended for use in modern high performance automobiles like SUV's, Vans and Light duty trucks requiring API GL-5 and MT-1 level performance

* Mobil 1 Synthetic gear Lubricant LS 75W-90 is intended for initial fill, topping-off or refilling differentials, final drives, transfer cases and other gear applications where lubricants meeting API Service GL-5 and multi-purpose or mild EP gear lubricants are recommended

* Mobil 1 Synthetic Gear Lubricant LS 75W-90 can also be used in rear axles where API Service GL-4 lubricant is recommended

* Not recommended for automatic, manual or semiautomatic transmissions for which engine oil or automatic transmission fluids are recommended

* Where extended service intervals and warranties are required

 

Have been using it for years now! Great product! :D

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  • 5 years later...

I just stuck to the OEM nissan gear oil with molyslip additive, and OEM Nissan diff oil. Gear changes are nice and smooth and no issues. You don't have to over think when it comes to gear and diff oil, if in doubt stick to OEM.

 

 

Sent from my iPhone using Tapatalk

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  • 2 years later...
On 17/08/2015 at 18:22, DarmoZ said:

I just stuck to the OEM nissan gear oil with molyslip additive, and OEM Nissan diff oil. Gear changes are nice and smooth and no issues. You don't have to over think when it comes to gear and diff oil, if in doubt stick to OEM.

 

 

Sent from my iPhone using Tapatalk

And now 3 years later.. how much molyslip should I put in?

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