so i read a few threads... and my previous post wasnt answered...

I have a 03' base model, 6speed, changing my trans and rear diff this weekend, so what I read a few people have said...

1.) since I dont have LSD with my 03 base model, is probably best to just go with Mobil 1 75w90 synthetic fluid? ($10 a quart) or just go with redline? (which would be kinda pointless because again, no LSD with the base model)

2.) Can I use the Mobil 1 75w90 in BOTH the REAR DIFF ANNNND the TRANS? Will it matter? Or go with the 50/50 mix with redlines MTL 70w80 (GL-4) and MT-90 75w90 (GL-4) 2 quarts each and mix them?

if someone can answer this that would be great help, i just dont want to mess this up...

 

01. It does not matter if you have the LSD or not in this car. The limited slip part of the differential is seperated from the oil you will change when draining it. To change the LSD oil, you will have to remove the cover. Draining the oil and refilling it will only allow you to change the ring and pinion gear oil.

02. I recommend using what the factory calls for. GL-4 for the manual transmission and GL-5 for the differential.

 

Just did this today along with an oil change. 08 Touring Z with almost 15k. Tranny fluid was pretty clean but what came out of the differential was a whole "different" story. Used almost 4qt OEM Nissan MTF and almost 2qt Royal Purple 75W-90 for the diff. Overpaid for the MTF ($14/qt) and RP ($19/qt) but got everything locally and didn't have to wait. Overall a happy camper - preventative maintenance FTW.

Word of advice: Wear clothes you don't care about! I did this all on a lift and even with the hand pump you're going to get oil all over you. Especially if you're doing this laying on the ground with jackstands and such.

Thanks for the writeup by the way. Made everything a whole lot more feasible especially tracking down the fluids.

 

The original post really needs to be updated. I was torquing mine down a few minutes ago and definitely went past spec before I said to myself this is definitely wrong.

It's going to ruin someones day and cost them money and a hassle and needs to be fixed asap.

 

maybe different model years have different torque specs... i'd suggest looking into your service manual for your model year

 

This is probably the case, but my point is that the information in the OP is misleading and doesn't specify a year or model as it pertains to anything other than fluids. So I checked the fluids in my owners manual and assumed the rest of the information is the same among model years. In the end it's my fault for not doing my due dilligence and checking the torque specs in the fsm for my specific model year. But any rational person can see that the misinformation can be damaging and should probably be ammended before someone strips their diff. Hell it almost happened to me and I consider myself a well capable mechanic.

 

bumping this

 

Some people have had success with Redline 50/50 while others say OEM is no worse and that it's all in the head. Hmm.. Debating whether I should give Redline a shot or save $10 and go with OEM......

 

If I just use the Z for track and drifting and have a cusco limited slip in, would running the redline mt90 and the redline 75w90 in the differential be sufficient oils to hold up at events.

 

I use MT-90 in my S13 trans with no problem. I rarely drive it. I had bad experiences with MT-90 in my daily driver G35. It seemed like MT-90 was too thick causing 1st-2nd gear grind in freezing temps during the first shifts of the morning and also a huge drop in mpg. Everything went back to normal with oem Nissan MTF. You're probaby ok using it in a track only car.

If you're running a clutch diff you might want to try Motul PA90. I run that in my S13 with 2-way Kaaz lsd. It's currently the smoothest it's ever been and Kaaz isn't known for smoothness...

 

Good thread, just changed my diff fluid today. Real easy, hardest part was getting my car on jack stands. after everything was jacked up it only took me 20min to change fluids.

 

Has anyone ever used ENEOS gear oil? And what about Royal purple?
http://www.kamispeed.com/ENEOS-Synth.../eo.en0mtf.htm

 

I have used Royal Purple 75w-90 in the stock rear vlsd. I did not like it at all! Where I'm from the winter temps can get into the low 30s, high 20s on the coldest days. From startup I'd get a horrendous howling from the rear for a few minutes until the oil circulates and heats up. I replaced it with conventional Castrol Hypoy C and everything in the world was good again.

 

Well, I live in Fl and i doesn't get past 30s it gets cold sometimes but not that cold, so not sure if it would be the same for me. i already bought it if it does act like yours ill swap it out and get amsoil. Thanks for the input.

 

True, you should be ok in your climate.

I also did experience a drop in MPG (~16mpg) using straight Redline MT-90 in the trans with the Royal Purple in the rear diff. I never pinpointed the cause, but as soon as I put oem Nissan MTF and the Castrol Hypoy C conventional everything was instantly back to normal (19-20mpg).

I first switched the fluids out late October 2008 and by December I was experiencing that horrible first start rear diff howling as temps went below freezing. It was definitely a pita changing out fluids in the cold winter outside lol.

 

it seems like everyone with a Z I talk too hates OEM fluid and I just dont understand??? I changed mine with all OEM Nissan fluids because I dont wanna void my warranty for something stupid and its working great for me so far..

 

As you can see from my post above I will always use OEM Nissan MTF in the transmission due to it's unusual viscosity (75w-85 iirc). In this case if "it ain't broke don't fix" is in effect. The transmission seems to be very sensitive to that. As long as it's oem spec any respectable brand should suffice. The Castrol Hypoy C seems to be working well in the differential for the last couple years.

Don't forget to save your receipts and mileage recording if you expect warranty coverage, but that's another story.

 

yeah, im going to return the royal purple, and go to nissan and get theres. Thanks for the info.

 

ya getting any warranty work done is a pain in the a** but I usually get what I want from Nissan. I do keep all my receipts and mileage too just for my own records.

 

How often should you change your dif's fluid?