At 3500 miles, I decided to change the MT and rear differential oil. This was done mainly for longevity, but I had noticed a touch of grab changing into some gears (especially 2nd). It wasn't to a grinding point at all... ...just a bit more grab to the notchiness.

I wanted to try the Lucas Gear Oil in both, but after picking up only the proper GL-5 for the diff., and because I was leaving town, I had the speed shop owner get the GL-4 gear oil that he's comfortable with for the 6MT. That happened to be Royal Purple.

The diff. feels great, and was much in need of the change, as it was thick, dark and dirty at only 3500 miles! I'm very happy with the Lucas Gear Oil for this application. Not sure what's up with the condition of the original OEM gear oil with so few miles... ...other than my G having seen hard cornering and some short trips.

Within the first couple of shifts, I could feel even a bit more grab going into some gears, which got worse with every mile. I put no more than 10 miles on it before deciding to make an appointment with Nissan (no local Infiniti dealer) and have the proper Nissan MT gear oil put back in. Memories of unhappy posts about the RP were on my mind immediately. With only 15 miles on the new fluid, the notchiness/grab had worsened nearly to the point of grinding. I was very gentle and consciously avoided any forced gearchanges, but that became increasingly hard.

With the fresh Nissan gear oil in the MT, shifts were immediately smooth again, to what I felt was the OEM notchiness. After 10-15 miles, shifts are even smoother than they were. I'm not sure how long the Nissan gear oil holds up, but it's clear that I got some immediate benefit (in shifting) from changing out the original fluid with only 3500 miles on it.

At the first sign of the grabby shifts returning and if the Lucas holds up well in the rear diff., then I'll be ready to try the proper Lucas Gear Oil in the MT as well. That, or frequent changes with the Nissan fluid.

Not much of a review, I know, so consider it just another warning that our 6MT doesn't like Royal Purple.

 

the gear fluid is good for 30k miles

 

I wouldn't put any Lucas treatments in there.

 

Jeff92se - Is that comming from personal experience with Lucas products? Initial impressions in the diff are good. We'll see how it holds up, and what it looks like (compared to the OEM fluid) when it comes out.

g35rcr - The original MT gear oil looked fine, but performance was starting to degrade. It happens that it turned out to smooth things up again, but it was more about longevity that it being dirty at that 3500 mile point.

HOWEVER, the gunk that came out of the rear diff after 3500 miles wasn't going to perform well at all for another 25,000 miles. Stick to those intervals if you like. I know I have with past cars. But with the G's 6MT not being renowned for it's longevity, a little more frequency on the gear-oil changes isn't a bad idea... ...especially for $150 or so.

If nothing else, I prefer to know what vital fluids are in the car and have piece-of-mind that they're in good condition. Turns out it was a good move for the diff.

FWIW, I encountered another fluid-based issue with my then-new '97 Mitsu. GSX. Several months after delivery, I got notice that some of the GSX(s) did not have enough fluid in the transfer case for their AWD when they left the factory. Mine was behaving fine, but it was in the affected lot. Took it in to the dealer and they found almost no fluid in there.

Now, certainly Mitsubishi deserves props for an AWD transfer case that could run on such little fluid without welding itself together, but the fluid oversight is another issue. Despite there not being significant damage (it did drive great still), everything new went in under warranty.

Yes, that's their mistake and they made good on it... ...but not all mistakes are such widespread or well known. If I had replaced the new fluids after break-in, I would have caught the lack of fluid.

Moral is, while it's not required, it's still not a bad idea to replace those new fluids after break-in. If the MT stays smooth, I'll still replace it within 15K miles to take a look at it. Then again, I accumulate miles fairly slowly but they are somewhat hard miles. I'm at just over 3500 miles in the past year. (small town, close to work, never road-tripped, etc... ...just enjoyed everytime it's driven)

 

GT-Ron, I had that exact same experience putting in Castrol synthetic lube to replace the OE in my 6mt. I had a tiny bit of notchiness before putting it in which the Lucas seems to have cured. I drove it maybe 15 miles with the Castrol and it was seizing up. I switched in the Lucas and within 5- 10 miles it was fine again. I have about 10k miles on the Lucas fluid and it still feels great.

In the diff the first change seems to be the important one and much better to do it way earlier than recommened as you have done. Mine was nearly black with a 1/2" of gunk around the magnet at first change around 4k miles. I did one more change at 11k miles more just to see if there was still some filings happening. The fluid looked clean and the magnet was virtually spotless.

I agree with you that changing fluids up often and initially before recommended is cheap insurance. I also accumulate miles slowly on my car 14K now since it's not a daily driver and stored winters. Some of the miles are hard and the car has been tracked as well.

G/L with your G.

 

Lucas and Royal Purple haven't offered enough publicly available data for me to trust them. Plus it's not clear if Lucas is compatible with Nissan's fluid.

Given the choice, I'd run either Nissan's stuff or Amsoil/Redline.

But it's purely my opinion

 

Thanks Jeff.

And thanks RBull. It makes me rest a little easier knowing your diff. fluid looked the exact same as mine. Also very nice to know that the Lucas gear oil that came out looked good after 11K miles.

If the OEM fluid in the MT ends up at the same point it was (prior to that first change) in 5000 miles or less, I'll switch it to the Lucas gear oil. At this point, I'm holding out hope that, like that original diff fluid, maybe the original MT fluid isn't so great from the factory.

 

i ran royal purple for 40k miles with no issues and then went back to nissan oem at 40k...so far ive put on 20k miles i asked my service tech when and he stated, "nissan fluid can go 30k" he is the master tech at the dealer that has done all my work, he could have said change it now to make some extra change but he gave an honest answer

 

You're welcome.

 

Will Redline synthetic GL5 work okay in the diff?

Is this an unusual kind of diff?

 

I have Amsoil in MT-forgot the grade, but they list it as the one to replace Nissan fluid. It works great, shifts are easy and car went through 2 track days and 3-4 autocrosses just fine.

 

Please do not put Lucas additives in your gearbox.

http://www.bobistheoilguy.com/images/lucas/lucas.htm

Who knows how their formulated gear lubes perform, but I'm trying to understand the benefit of using their stuff over proven performers like Mobil 1, Amsoil, and Redline. Go into the pits at Infineon or Laguna Seca and take note of what you see.

 

Redline transmission oil and engine oil rule

 

I still use and prefer Shell Spirax 75-90W GL-4/5 full synthetic gear oil and now I'm using it in the rear differential. Good multi-purpose product with lots of real world test results. Super smooth shifting and no more high RPM gear gear crunches.....ever

 

The royal purple trans fluid you should have got is called "syncromax". Its smoother on newer trannys vs the plan ole MT fluid. I used to put syncro-max in my SRT4 every 7-8k miles, but it was almost all race miles.