Nissan 370Z Forum - about ATF

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Quote:

Originally Posted by bvl (Post 1346132)

The WS6 is a manually: different fluid properties. Many trannies tend to like a particular additive package a tad more if you are that sensitive to shift feel (you trade off smoothness for bearing wear over a long time. Few good docs on this, including Redline as they make several different packages for manuals and diffs)

As you note: dirty does not mean bad. Unless you run an analysis on the used stuff, you don't know the additive package and fluid composition. Regular motor oil will darken in 1-2K (if not less) miles but is working just peachy.

100K maintenance free is really a demand of consumers: they feel its a hassle to maintain a car (face it: most americans can't check air pressure, its sad but true).

That said, most manufacturers have 'premium' style service intervals which do still replace fluids more aggressively. Varies by car of course. Diff, transfer, MT, AT, and brake fluid are just a few that often go un-maintained.

- b

Lets put it this way, the WS6 did fine until I swapped trans fluid. Then it was a bit harder to shift in the cold it seemed. Fluid was OEM spec from Prestone.

The rear-end was fine until I changed that, too. Went with Royal Purple 85-140 synthetic, as it had a mechanical worm-gear type posi. After destroying the pinion-bearing and a set of axles within a few thousand miles...screw Royal Purple.

Point is, the car was fine until I started "maintaining" the fluids.

I should have learned my lesson on my '95 Trans Am, which was a PITA to get right again after doing the diff fluid in that. IT had an auburn style posi and we monkeyed with mixing the right amount of anti-slip addative for quite some time before it would again go around corners without shuddering.

Then I tried the same thing on my G20 because "It's an import".
Fail.

JUST LEAVE IT THE HELL ALONE!

That's the best advice I've got. It was told to me my whole life, I defied it and ended up with a blown rear-end on my WS6 and a dead transmission in my G20. I learned my lesson!

Manufacturers don't say "Maintenance free" out of convenience. If that were the case, timing-gear belts would also be "maintenance free". Well, they aren't. They cost a lot more to replace than transmission fluid, but if you don't do it, well, I have seen plenty of mangled heads because of that. I have never ONCE! seen a transmission or rear-end that died because the fluid was not changed. They have died because of being operated in an over-heated condition, but never once did we have one come into the dealership dead due to "dirty fluid". In fact, there was only only car that came in for fluid related issues regarding "lack of maintenance" while I was at that Ford dealership (A period of 1 year). A retro style T-bird with a siezed engine and IIRC 28K miles on the odometer. OEM oil/filter. Even then, it seized because of LACK of oil in the sump/engine, not "dirty oil".

I have always been told "If the transmission fluid is black, it's because the transmission has a problem and putting new fluid in will kill it almost immediately. If it's red, why change it? So just don't **** with it."

Well, I dicked with it in my Infiniti because the fluid was VERY LIGHTLY red/gray/I thought I was special and could replace the fluid and make the car better off for it. It got me a dead transmission just as promised.

With an AT if you let the fluid get trashed and flush it out, you're likely to free up some deposits in the transmission and that can cause problems shortly down the road. AT fluid has great cleaning properties for the transmission but that can cause trouble with a lot of miles on the vehicle and old fluid. I purchased my 1998 Jeep Cherokee XJ in 2003 with 120k miles on it. Most people said don't change it since it had never been changed at regular intervals (mine looked horrible). I changed it anyway (yeah, I'm smarter lol) but I did several drain and fills of the AT fluid pan. It was a gradual change of the fluid over the course of a year (each oil change) and never had an issue. The AT was going strong when I sold it with 185k on the clock.

On my S2000 I change the MT oil and differential oil once a year (about 9k miles of use). The MT gets a little notchy after about a year and new fluid solves the issue. Since the car is up on stands already and it's only 1 quart, I throw some new Mobile 1 gear lube in the diff. Never had a single issue with that.

To each their own, but I disagree that the fluid should be left alone for good. Things wear out and particles become suspended in fluid/oils. Also, water can be absorbed into the fluids as well and that doesn't help. If I planned to keep my Z past the 100k mark I would probably change the AT fluid every 40k miles or so. However, since I have the extended warranty and Nissan calls for no replacement, there's no need. I factored this into the cost of the warranty as it technically reduces the cost of the warranty since I'm getting out of a couple AT fluid changes (again, because I think I'm smarter than the OEM ;)).

I've heard of too many horror stories about changing
the fluid. On these new Closed AT you can't even check
the fluid level