I have been reading up on manual transmission gear oil and wasn't planning to do anything to upgrade the gear oil in my car for about another 10k, but Nissan just replaced my clutch (under warranty and it feels MUCH better than before) and also had to replace the gear oil. I don't know what brand they used, but I do know it was an 80-90 GL-5. I think they made a mistake by putting in a non GL-4 lubricant.

Nissan owner's manual calls for GL-4. Internet research indicates that Sodium based detergents in GL-5 can destroy Brass and Bronze parts (such as syncros). Apparently GL-5 has a few times greater concentration of these chemicals that kill syncros.

I searched the local autoparts stores for 75-90 GL-4 and nobody has it anymore. I did find a local Valvoline Quick Lube who "claims" to have Quaker State 75-90 GL-4 in a big drum, but I'm not sure I trust that . . . they wouldn't order me quarts of GL-4 and gave me a story that the stuff was really expensive - it wasn't even a synthetic.

So what should I do? I don't want to risk my syncros, I can't afford to rebuild my tranny if 30k. I would consider synthetic, but which one? The Mobil 1 75-90 GL-5 web site overview specifically states NOT to use that product in tranny's that require GL-4. If GL-5 is ok for our transmissions why would Mobil tell us not to use their product in our 6 speeds?

I almost think that a GL-4 synthetic would be optimal, but I don't even know if that exists.

I am looking for suggestions, opinions, options and comments. Thanks!

 

The lubricant has to be specifically formulated to provide a GL5 level of protection, but still be safe to use in a GL4 transmission, which can contain softer metals that can be eaten. You probably won't find an petroleum GL5 that does this. Mobil 1 also does not do this, which is why they don't recommend it's use. Redline and Amsoil are the two synthetic gear lubes that would be safe for your transmission.

Amsoil can be purchased for about $30 and you'll probably sell the car before it needs to be changed again. Email for a specific price quote.

 

I would consider Amsoil. Which product in particular would you recommend?

 

go to www.racerpartswholesale.com click on redline on your left, then transmission oil, then click on the correct oil weight you need and then check out! it maybe expensive but it will save u alot in the long run. great stuff, i ordered from them. and its synthetic!

 

Redline MT90 worked great for me. Bought it from www.autoil.com. Good luck.

 

do not buy more than 4 quarts, I am pretty sure my 2K1 took 3 1/2 but that was so long ago I cannot remember.

 

Either the Series 2000 75W-90 or the 75W-90. The Series 2000 is better overall, but if the car doesn't see the track at all, the regular 75W-90 is fine. More info on them is here: http://www.mdvsynthetics.com/guides/gearlubes2.htm

The 2K2 6 speed hold 2 1/2 qts., so you need to buy 3 quarts to ensure you have enough.

BTW - The Series 2000 actually will provide a thicker film at operating temperature than Redline MT-90. It also costs less and is backed by a warranty.

 

I am very seriously considering the Amsoil. I spent a good part of the day today researching the Amsoil products. Could you point me to some web sites that provide independent tests of the Amsoil products? Most of what I was able to find seemed to be sponsored by Amsoil itself.

In one of your posts on Maxima.org, I think you stated that you had tried the RedLine MT as well as the Amsoil and that you liked the Amsoil better. Could you describe the differences you observed?

My biggest concern is that the friction levels will not be appropriate for the synchros. I currently feel the synchros "grabbing" when I shift - even on slow shifts - and this was not previously true until the fluid was changed by the dealer.

Do you also use the Amsoil foam air filters? If so, do they make a cone style product that could be used with an after market intake, like the Injen?
Thanks for your input!

 

In terms of gear oil, unfortunately I can't. The best thing I could point you too is bimmerforums.com There are real world comments from those guys on what they think of it. There's also Redline's own datasheets which you can find here to compare the two: http://www.redlineoil.com/products.htm , if it doesn't come up directly, you can look under technical properties in PDF format.


Don't get me wrong, Redline is still an excellent product, but it is geared toward maximizing performance, not wear protection. For me, I'd rather have the wear protection, especially in a street vehicle. Along these same lines, I don't want to pay more for a product that doesn't protect as well. If I had a dedicated race car that I competed with, Redline would be the better choice, but my car is a daily driver. The biggest thing I like about Amsoil is the company will stand by their products with a warranty. To me, that kind of confidence in a product means something.

Friction coefficients and synchro wear came up in another thread. I emailed Amsoil tech services about it, and their response basically said the friction coefficients are essentially the same, and the Series 2000 is not more "slippery". The main advantage is superior film strength and it's high resistance to thermal breakdown and oxidation.

I haven't tried one of those yet, I had the Popcharger on my car before I knew they existed and I'm too cheap to replace it right now. For an aftermarket intake, I don't think Amsoils filters are an option. Hope this helps some.