OK! Who doesn't know their head from their ass!! GL-4 and GL-5

I am at a complete loss here. Forum members are saying GL-5 is bad because it has Sulfuric something or other. Others says GL-5 is fine and are using it.

So, I went to the local dealer and spoke with them for a while in regards to the differences between GL-4 and GL-5. They seem to think that GL-5 is an upgrade to GL-4. They also stated that Nissan specifically trained them on the GL-5 gear oil. Nissan sends all dealers preselected gear oils per Nissan's own recommendations. And guess what? The dealer stated that the ONLY gear oil Nissan sends them for all manual tranny applications is Castrol Hypo-C GL-5 Gear Oil. NOT Castrol Hypo GL-4, but Castrol Hypo-C GL-5.

Anyone have and hard facts that validate that the SR20DE tranny can not handle the GL-5 gear oil without major issues in the future?

I have about had it with trying to find a standard GL-4 gear oil without having to pay $7.99 for freaking MT-90 when you can buy a quart of GL-5 starting at around $2.00 and up. I am sorry, but there has got to be another source for GL-4 gear oil besides Redline and Purple.

I am gonna search for the Castrol Hypo GL-4 gear oil and hope to find it. Castrol's website states it is in a shitload of retail stores, but I have yet to find it hear in Ohio.

Anyones thought on this?

I find it odd that the dealership you called said to use GL-5. I called 2 dealerships and both recommend GL-4 for manual transmissions. Also Mobil NZ recommends GL-4 for Primera manual transmissions.

As for the sulphur thing, EP additives contained in many GL-5 oils are often made of sulphur phosporous compounds which are corrosive to copper alloys such as bronze and brass. Can anyone confirm what the RS5F32A gearbox synchros are made of? (pretty sure they are bronze)

Here's a quote from this site http://www.pennzoil.com/carcare/faq/default.htm#4

"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 ."

So to answer your question, your local dealer doesn't know their head from their ass.:finger: :D (Unless they have a GL-5 with no sulphur content ... yeah right)

Which grade of Hypo C did they recommend because on http://www.castrolusa.com/products/productpage.asp?product_id=16&product_category=3 they specifically state that 2 out of the 3 grades are for "non -synchronized manual transmissions" while the other is recommended for LSDs. From the Castrol site, I get the impression that your dealer recommended truck oil.

Thats it! Thanks T4! It seems like everyone always states that it's bad, but no one really gave a reason why. I researched it as much as I could and was only able to find little tid bits here and there. Castrol's website seemed to be the only site that shows a GL-4 Gear oil.

The dealer actually uses the Hypo-C GL-5 which I believe was 80W90 grade. He pulled out a bottle and let me read the back of it. I went to Castrols site and saw the Castrol Hypo GL-4 80W90 which looks like the route I may go if I can find it. Here is the one I am trying to find:
http://www.castrolusa.com/products/productpage.asp?product_category=3&product_id=15

http://www.castrolusa.com/products/productimageslg/Hypoy_Gear_Oil_L.jpg

I read SE-R.net and searched the SE-R Digest and both pretty much states use MT-90 cause it's the best. Not really explaining why or what other alternative gear oils there are.

I am going to look at the link you provided for more detail as well as Castrol's site again. Thanks!

Oh I forgot, Haynes manual #1851 for Nissan Primera also recommends manual gearbox as: Hypoid gear oil, viscosity SAE 80W to API GL-4:)

Just had a thought (ouch!) that may have a bearing on this. Some of your North American cars are fitted with limited slip diffs. Since the diff and gearbox are combined oil-wise, maybe there is some difference in the oil specification. Can somebody with a Factory Service Manual post what oil it specifies for the G20 (and G20T if different).:o

Atleast for the 1996 G20, the owners manual states GL-4.