about ATF

ImportConvert

I wouldn't screw with it. My G20 had never had its fluid changed that I know of, and at 110K miles I had it changed as I was told import cars were different that domestics (I was new to the import world then) and that you can change fluid in the transmissions without it screwing things up. Well, I liked the little car and it had done well for a few weeks and I wanted to treat it, so I had them (dealership) drain and re-fill. No flush, just a fluid swap. It died at 115K miles. Slipping horrible, etc. Now I have heard that if you do it every 15-30K miles when new, this won't happen, but the manufacturer says not to, so why the hell would I?

My 2001 WS6 was a 6-speed, and I had the fluid in it changed (@75K miles). It didn't have any problems afterward, but it never shifted as smoothly in my opinion.

So I'm just not a fan of messing with it.

Just because it LOOKS dirty doesn't mean it's not working just fine. Anyone who has ever checked the oil on a diesel can tell you that.

Nissan says not to screw with it. Do you really think their master-plan is to have your transmission go out at the 100K mile-mark and that's to be their big money-maker? Seriously? Just don't **** with it.

My .02

bvl

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

ImportConvert

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".