Thanks for the link
So API MT-1 is the new GL-4.
Still no go for diff's though.

 

As far as I can tell, we only have MT1 and GL5 for current gear oil ratings now. But of course, we still have MTF, MTL, ATF and ATL for transmissions. I don't think API has any oversight or rating system for those lubes though.

I wish they would make an attempt at GL6 again, but they (API) don't even seem to have their arms around GL5 yet!

 

Called local dealer to get air filter (which by the way almost impossible to find in stock) also asked question about diff oil. Guy said they buy GL-5 in local parts store....waiting till 9am to call HoA, and then will call morons at servicing dealership.

 

It could be that automatic trans fluids are not recognized (by API) as "gear oils", more like hydraulic oils?
As far as all the manual trans fluids on the market goes: isn't it up to the manufacturer to get the oils tested according to API specs?


The fact Honda recommended GL-5 / GL-6 in the first S2000 manual is IMO a sign they thought the diff needed it.
Small diff, powerfull engine, high offset (= displacement of axes) hypoid gears, less than a quart of oil in it: it is not hard to understand how Honda came to this conclusion.
1+1=2.. its pretty easy

 

I'd swap it for some GL-5. Manual states GL-5 SAE 90, but Honda laxed these requirements due to the lack of straight 90 weight fluids being available.

 

HoA is not much help.....they just take the complaint and contact the dealer.....its up to dealer decide if they wanna keep screwing customers or finally follow the manual. HoA said that dealer should get in touch with me, but for some reason since service was not under my name and was not paid by me.....they might just ignore me.

 

No one got in touch with me, called HoA again, they said they cannot help me any further and even if they put engine oil in rear diff. they still wouldn't be able to help me...

So should I just drop this and change oil myself ? and let the dealer screw other customers....or should I just sue them for new differential in small claims court ? < sound like a 100% win case to me....says GL5 in manual, and says GL4 in service record.

 

If it was me, I probably would just buy some GL-5 and put it in myself. It really is an easy process. Drain and fill. 2 bolts. You'll never get anywhere with either HoA or the dealer, and screw the court fees too. Just swap it out. It most likely hasn't caused any damage yet so just get it out of there before it does.

 

switched to M1 75w90 LS today myself. bought last 2 washers from dealer didnt use torque range so hopefully no leaks....

I am still so pissed at that dealer, i am just itching to sue them. court fee is only like $20 bucks.

 

What did the mysterious GL-4 fluid look like coming out? Any visible debris ("sparklies") in the old oil?