[NismoPC]

Well I emailed my local Nissan dealer this letter 2 days ago and still no reply. I will assume that I will no get a response from them.

Toby

I was recently in your dealership purchasing some oil filters and a cap & rotor for my '96 SR20DE and had asked you what Gear Oil to use in my manual transmission when I replace my clutch. I just wanted to forward some information in regards to why I was told that we should not use GL-5 gear oil in a GL-4 specific transmission.

Would you please forward this information to the person you had referred me to in regards to the Castrol Hypo-C 80W90 Gear Oil that he stated Nissan recommends for the SR20DE powered. (I believe he is the parts and or service mgr.) I believe that the Castrol Hypo 80W90 (not the Hypo-C) should be the actual gear oil used in these transmissions. It is specific for GL-4 only applications. He had also state that the GL-5 is an upgrade to the GL-4 gear oil. That, according to what I have read, is incorrect as well.

NOTE: I also looked through several SR20DE owners manuals between the years of 1991 and 1999 (NX2000, SE-R, 200SX SE-R, SE, G20) and all of the owners manuals also specifically state to use GL-4 gear oil.

Since I was unable to give the technical details of why I was told not to use GL-5 gear oil, I copied the following insert from Pennzoil's website.

[Quoted from www.pennzoil.com]
What happens if API GL-5 gear oil is used in an API GL-4 gear oil application?
API GL-4 and API GL-5 products typically use the same extreme pressure (EP) additive system, with the API GL-5 having about twice the concentration of a API GL-4. In service, these additives become active under extreme load and temperature when the protective oil film can be squeezed away. EP additives work by forming wear-resistant compounds with the metal of the gear tooth surface. As the gears mesh, these compounds shield the gear teeth from direct metal-to-metal contact that would cause wear and damage to the gears. If too little of the active additive is present, proper protection would be compromised. Too much of this additive could cause excessive chemical corrosion of the gear surface. If an API GL-5 gear oil is used in a application where API GL-4 gear oil is called for, chemical corrosion of "yellow metal" components may occur, such as bronze synchronizers, brass bushings, etc. This may lead to shifting difficulties or shortened equipment life.
[End Quote]

Here is more info on the Castrol Hypo (GL-4) gear oil I believe should be the recommended gear oil:
http://www.castrolusa.com/products/p...&product_id=15

I am part of a large community of SR20DE powered vehicles across the US as well as New Zealand, Australia, and Canada, and other parts of the world and a concerned consumer who has great interest in Nissan/Infiniti products and proper maintenance of those products. Because of this, I will be purchasing the Castrol Hypo 80W90 GL-4 specific gear oil and feel confident that I made the right choice. I just hope that your dealership looks into this and makes the right choice as well.

Also note, my wife and I purchased a Pathfinder from your dealership two years ago and I purchase all of my Nissan/Infiniti parts from your dealership. I am very pleased with the service we have received over the past 7 or so years. And I plan on dealing with your dealership for many years to come as well. We have never received the quality service that your dealership provides from any of the other central Ohio Nissan dealerships. This includes car sales, service, and parts dept.

Thanks!

As you can see, I couldn't even find the Castrol Hypo GL-4 so I went with the Valvoline 'cause it was all I could find!

If they do reply, I'll be posting it!