After reading multiple Dino vs. Synthetic M/T gear oil threads, I'm trying to get a feel for the experiences of people that have made the move to synthetic in their 2k2-2k3 6-speeds. It seems synthetic was liked across the board for 5-speed owners, but 6-speed owners have had varied experiences.

In short, those against synthetics have argued that it causes problems for the synchronizers because it is often too slick for the synchros to function efficiently. iwannabmw countered by speaking with Amsoil tech support directly: "The tractive coefficient of a synthetic is essentially the same, in other words, the TGR is not more "slippery" than other fluids. The main advantage of TGR is its superior film strength and it's high resistance to thermal breakdown and oxidation."

I'm very interested in making the move to synthetic for the additional protection, but would like to see how many people have had negative experiences.

 

I'm planning on switching to the MT-90 tomorrow. IIRC synchro problems were caused by peeps using a GL-5 formula in their 6 speeds. As long as it's a GL-4 (like MT-90) there should be no issues.

 

Nope, some have used the aformentioned GL-4 synthetics and had issues. Just wanting to see how common the problems are...

 

Man, I hope any problems are few and far between...........

 

run Royal Purple MT with the LSD stuff. I have it and it rocks

 

Has anybody had any bad experiences with synthetic GL-4 MT oil? The few responses in the poll indicate no.

I put MT-90 in my 2K2 today and MAXimumHP put some in his 4th gen 5 speed. I'm hoping there will not be any problems......

 

Yes, people have had bad experiences. Here's is just one thread with examples:

http://forums.maxima.org/showthread....hros+synthetic

In short, SR20DEN summed it up:
I keep trying to warn everyone but no one wants to listen.
Folks when you put synthetic gear oil in your manual gearbox it causes problems for the synchronizers. The oil works wonders for everyhting else but it is often too slick for the synchros to function efficiently. I destroyed a gearbox on my '98 Maxima in 30k miles from running Motul semi synthetic. Every single Nissan vehicle I have driven I have put synthetic gear oil in and it always turns out the same results. Premature syncro wear because the friction modifiers don't work right.

Here was iwannabmw's response: (an amsoil dealer
Well, I've personally used it two Nissan vehicles that were driven hard. The first was a 95 Altimas that went 84K. The tranny shifted like new throughout it's life. It died when it ate it's bearings. The second is the 97 Max I still have, 74K extremely hard miles. Considering the way it's driven, the transmission's doing great. Video Note the speeds of the shifts.

I'd bet most of your issues are driving technique. Contrary to what some people think, sythetics don't let you shift any faster. You can't slam through gears, which is probably what caused the premature synchro wear. That and the amount of power you manage to put through it...

On another note, about the coefficient of friction issue, I tossed the question to tech serivces. This pretty much sums up their reply: The tractive coeffiecient of a synthetic is essentially the same, in other words, the TGR is not more "slippery" than other fluids. The main advantage of TGR is it's superior film strength and it's high resistance to thermal breakdown and oxidation.

My note: I've heard and read claims on the .org that amsoil actually does claim their synthetic is slicker. I have yet to hunt this down in writing...

 

Thanks for the info, housecor. I'm not sure what to think. The MT-90 is in my tranny...guess I'll have to monitor it for any signs of trouble. Or I could replace it in the spring and send a sample to Blackstone and see if they find anything....

 

I'll be interested to hear your experience over the next few months. Also, it just hit me that many .org members who choose to upgrade to synthetic do so because they know they drive their car hard! Likely, many running Amsoil and Redline like to autocross on the weekend and live for running their Max to redline. I mean, this is an upgrade for enthusiasts. I've gotta wonder if the few instances of synthetic users with worn out synchros are simply people being abusive to their tranny!

 

I was running the Amsoil approved for my tranny's GL rating. It shifted just fine. Superior film strength and much superior cold weather performance.

 

It could well be that 'abuse' causes or contributes the the synchro problem. I will drive in a 'spirited' manner at times, but I don't drive my Max hard anywhere close to all the time and I don't shift really hard. I've never done auto-cross (although I'd like to give it a try) and only been to the track once. Time will tell, I suppose....as long as it's before the 3/36 is up!!

 

bump

Looks like no one who mentioned they've experienced issues has chimed in...I know you're out there!

 

Non Max related, but I am very into the 300Z community as well and have always recommended MT-90 for anyone wanting to upgrade a Nissan tranny for more "spirited" driving. The one 'downside' is that there is about a 500 mile break-in period where you really don't want to shift too fast or hard (similar to breaking in a clutch, I guess you could say). I waited about 1000 miles on my vehicles. After that, shifting was absolutely amazing. Cold weather performance was terrific as well...

My disclaimer is that I have no experience with the new 6-speed trannys so I will offer the above as food for thought. If you have patience to let them break in, Nissan synchros tend to love MT-90.

 

I am going to give the Amsoil 80w-90 a try in my next gearbox. I think all of the synthetics I have used (Motul, Valvoline and Mobile 1) were all 75w-90.


Also a good friend of mine who works at a transmision shop actually recommends ATF for manual gearboxes in certain situations. He claims to have used it in a RS5F32V (SE-R tranny) and it solved a few noise problems etc. .

 

FYI, I got the itch to check my tranny fluid level this weekend. Level is fine. A little fluid dripped out from the filler hole, and I noticed it is the same yellowish-clear color, and the exact same smell, as brand new Redline MT-90 which I put in. This is after ~15K mi I believe. Good stuff

 

Alright, your post put me over the top - I ordered 3 qts. of MT-90 tonight. I'll post with my impressions after the swap. Thanks for the input!

 

Im thinkin about puttin MT90 in my 6th gen. Is it hard to do it yourself? I have never done it but I think I could handle it.

 

Check this link.....

http://maxima.cardomain.com/memberpage/313356/9

housecor did a great job with a write up for his manual transmission 5th gen. I would think yours would be very similar. Very easy to do....

 

9 years later....Run Amsoil or Redline?