As has been discussed previously in this forum, there is some question as to what is an acceptable transmission oil to use in Xterra manual transmissions.

The Nissan spec calls for a GL4 gear oil, presumably to avoid additional sulfur-based additives in GL5 gear oil that may damage soft metals in the transmission.

However, it's pretty hard to find a 75W90 GL4 gear oil--which is what Nissan recommends. It is easy to find a 80W90 GL4 oil, but for people that live in cold climates like I do, 80W90 is just not an option.

I became concerned because I have been using Valvoline SynPower (full synthetic) gear oil in my transsmission. It's a GL5 oil.

I called Valvoline (800-832-6825) and spoke to a tech person and was told that SynPower uses a "non-active" form of the sulfur additive that will not damage any soft metals in a transmission and that SynPower was safe to use in any application that requires GL4.

Finally, while SynPower is probably safe, it's also a lot more "slippery" than non-synthetic gear oils, meaning that you may have to shift more slowly (expecially between first and second gears) to allow the synchronizers to "catch up" because the gear oil is so slippery. That would apply to any full synthetic gear oil.

I live in Gunnison, Colorado, where it's quite cold for much of the year. When it is cold, my transmission (with Valvoline SynPower) is totally perfect. However, in the summer months, I find I do have to shift a little slower than I would in the winter, especially from first into second.

xterrascott,
Unfortunately I have a slushbox in my Xterra, but in other vehicles, I've used RedLine MTL and MT-90 with success. That includes the Rovers which have many more "soft metal" bits than modern trannys. I've had no cold shift problems at all. Both of these fluids are safe for the GL-4 recommendation...
Bogatyr

Interesting. My shifting experience has been the opposite. I put Royal Purple in last winter, also a full synth. When it's warm out (or when the tranny is fully warmed up), I can shift as fast as I like but in the cold, I have to pay attention and use some effort when going from 1st to 2nd. No grinding or anything, just hard shifting.

Mines behaves like that too. I have standard Nissan oil from the dealer.

http://www.xterraownersclub.com/cgi-local/ultimatebb.cgi?ubb=get_topic;f=45;t=001211#000000

silverxglider,
What are the specs on the Royal Purple gear oil? From the used oil analyses I've read of Royal Purple on the Bob is the Oil Guy site, I haven't been terribly impressed with the product.
Bogatyr

just wondering about the manual tranny issues and thought maybe you guys might help. took the truck to the dealer for the 30K service, mistake, and the tranny hasnt been the same since. on startup in the morning when approaching a light i have to literally ram the shift lever to get back into first gear. up shifting is easy but putting it back down into first is a herculean effort. any ideas or help would be great thanks alot.

xterra312002,
Did they change out the tranny fluid? If so, what did they put in there? Is your shifting easier once the tranny is warmed up? Do you have any trouble downshifting? Is the clutch fluid level ok? Do you get any grinding when going into first with difficulty?
Bogatyr

Along with the questions in Bogatyr's post, I'll add, do you double clutch for the down shift?

dave and xtoy - lug it in second

My experience is well documented here:

http://www.xterraownersclub.com/cgi-local/ultimatebb.cgi?ubb=get_topic;f=45;t=001211#000000

Thanks for the link - I forgot about that thread. I unwittingly contributed a few one liners

As I said in the other thread, for me going into first gear (if the truck is moving or stopped) is impossible without double clutching. I could try to just jam it, but I really don't want to force it. I can up shift with no problems.

Have the factory fill, but always watch these threads with intrest to see if anyone has found anything better. As I suspected, in finishing the other thread it looks like Redline is out (as it was on my 240sx).

xterrascott - you say SynPower works great when it gets cold - what temperature is "cold" to you? It's probably relativly temperate here in DC compared to Colorado

IIRC, RP is supposed to be GL5 and GL4 compatible. More than that I do not know.

My shifting problems began when the dealer put in Mobil GL5 80W90 at 30,000 miles. When I realized what they used, I put RP in at 40,000 but I did not really see any improvement. I may well try Redline next time.

they definetly changed something since there was residue around the drain plug, as for the other questions only when cold start in the morning and into first hear but gets better through out the day. no grinding, yet!!! the funny thing is that i never had any tranny issues until the dealer did their so called "service," they did a service all right, thanks again.

sorry forgot something, any suggestions on what i should do????

xterra312002,
If I had the symptoms you describe, the first thing I would do is swap out the fluid. I'm wondering if Nissan swapped it out with something incompatible like ATF
Bogatyr

First of all, I changed my tranny oil to AmsOIL and I have similar problems. I have difficulty getting into first gear when I first get going on a cold morning too. What I do is ** very carefully ** let the clutch out, very slowly until it pops into gear and then immediately push the clutch pedal back in. Presto, the transmission is in first and I didn't have to force it. Of course if you let the clutch out too much, you just grind the syncros.

Give it a try.

My mistake *I use that method to get into REVERSE*

The best solution is to tell dealers and quick change oil places is what YOU want put in the boxes, not just what they happen to have laying around. That way, you do a little research and know what's supposed to be in YOUR vehicle, and some grease monkey doesn't grab the nearest handle of "bulk lube".

How often should we replace manual transmission fluid?

this is my first manual vehicle.

thanks,

mel

Did your X come with an owner's manual? The maintenance schedule includes that info.
Every 60,000 miles is the interval.

Brent

I am using Red Line MT-90 synthetic manual transmission lubricant. It is a 75W-90 gear oil rated API GL-4. It has worked well both hot and cold in my Xterra. This product is not particularly cheap nor easy to find locally, but it seems to be one of the few compatible gear oils for the X. :rolleyes:

You can buy redline MT 90 (75w-90 GL4) fluid from:

http://www.lightningmotorsports.com/redline.htm

I'm going to get some to replace the crap the dealer put in my Xterra that makes it hard for my wife to shift gears when its cold out.

Good god! I just got off the phone with Nissan and they are recommending 75W85 at $12 qt! What the hell?!?! Only reason I've called them is that I can't find anybody else in the area that sells the crap... any input on that one?

Did the dealer say who makes it? Is it a synthetic? $12 is a lot if it's not synthetic, if it is then that's the best price you're going to find on a synthetic 75W-85.

I posted somewhere else that there are lots of 75W-85 GL-4 lubes, but none are available in the U.S. through regular retail outlets; probably because so few people even buy cars with manual transmissions in this country anymore! The best I've found is Castrol SynTorq, which is sold through GM and Chrysler dealers as the only approved oil for the NV4500 transmissions they use. It runs $20-$30 per quart! I use it in my Xterra and it's absolutely the best gear oil I've ever used, but I don't know if I would spend that much again.

The next closest match that you can find retail is Redline MTL, which is a 70W-80+ GL-4 lube. The viscosity numbers are lower, but according to Redline it has similar performance to a 70W-85 lubricant. Plenty of Nissan people use it without problems.

Anyway, after switching to 75W-85 I can see why Nissan changed the oil spec. on the tranny. It definately works much better than the 75W-90.

He said it was just a Nissan brand, which didn't really make a lot of sense to me... I'll have to drive over and check it out...

Again, try a marine outlet. Lower-unit lube is GL4.

I use Redline MTL in my trans. I haven't had any problems shifting cold, or warm.

I just ordered the oil online. There are any number of sources for Redline, you should be able to find it for about $8.00 a quart.

If you are having trouble shifting when it's cold, be sure to check your clutch fluid. It's just brake fluid, and that's hygroscopic. Over time your brake fluid and the fluid in the clutch line will absorb water. The water migrates to the bottom of the system when you're parked. In the case of the clutch, this is the slave cylinder at the clutch.The result is a mushy pedal since the wate will compress but the brake fluid won't. Cold makes the problem more evident.

Bleading the clutch system might solve the problem.