I have the Haynes manual and it says 75W-90 GL5....but have just been told by a guy on the phone at the local holden dealer that they put auto fluid in manuals. Asked him to double check and he said yep that's right...but i have never heard of this!
it's very common in the tremecs (v8) cause they are so bloody aweful. i have been in contact with redline oils for a oil for my ve sv6 6speed(same box as vz) the said you can use there 75-90 NS oil but they recommend the MT-90 oil which is actually a GL4 oil but they reckon it gives the best results.
Oh oh, is this going to be another preferences thread like tyres, engine oil etc.....? :whistling
I have been researching......the Haynes manual sez GL5 and from the bits I have collected below I'd not be keen on a lwer spec i.e. GL4....I will try and find a definitive answer in my Holden service book or something. Anyone have the service schedule handy? Mine is at home...
Plus this is a write up on a comparison of GL-4 and GL-5:
GL-4: Specified for hypoid gear service without shock loading, but still moderate to severe service (high speed/low torque and low speed/high torque). These lubes may be used in manual transmissions and transaxles where EP additives are acceptable and typically contain a different zinc additive combination. This classification is still commonly used, but is also obsolete. It is also a commonly specified for marine outboard and stern drive lower unit gears and bearings where the manufacturer specifies GL-4 rated performance. GL-4 rates lubes are not recommended as a replacement for GL-5 rated lubes. “GL-5 rated lubes shows significantly better anti-wear (anti-score) properties than GL-4 rated oils under similar service conditions”
GL-5: Specified for hypoid gears under shock loading and severe service operating conditions used in cars and trucks. This is the most common and widely used specification today. These lubes have a high level of EP additives and, depending on the manufacturer and formulation, could be mildly corrosive to non-ferrous parts in certain applications.
The major difference bettween GL-4 and GL-5 quality lubricants is in the amount of extreme pressure chemistry that is used in the formulation of a EP gear oil. Generally GL-4 gear oils contain 50% less extreme pressure chemistry than GL-5 type gear lubricants.
The API GL categories are meant to be progressive. In other word a GL-5 gear lube will cover all of the specifications below it such as GL-4, GL-3 etc.
Also one should note that not all EP gear lubricants use Sulfur-Phosphorous Chemistries. The other EP chemistries that can be used are Borate Chemistry and Sulfur-Phosphorous-Boron Chemistries. Regardless of the type of chemistry used you will find that all of these chemistries will not attack brass,bronze and other yellow metals unless something causes them to radically breakdown. Generally this is contaminants and is some cases extreme high temperature operation. In some cases if the ep chemistry is not thermally durable it can undergo radical changes in its chemical structure causing the formation of deposits and a loss in its extreme pressure protection.
GL-5 gear lubricants can not be used in all applications that call for GL-4. For example some transmission applications mainly found in pickup require the use of GL-4 quality gear lubricants because of the presence of syncronizers, syncromeshs and frictional clutch plates. If a GL-5 gear lubricant was used in these applications it would provide to high of a frictional modification characteristics to allow these mechanisms to properly engage and function.
Finally MoS2 (Molybdneum Disulfide)is used in some gear lubricant formulations as a friction reducer and additional antiwear additive. By itself Molybdenum disulfide will not allow a gear lubricant to meet GL-5 much less GL-4.