I have over 71k miles on my Z and I plan on keeping it for a few more years. I have been running synthetic oil since day one and I have never had any engine trouble. I stopped going to the dealer for service and use a local garage to do the same stuff (i.e. had radiator flushed at 60k)

I was wondering at what point should I worry about the following:

Changing the rear differential fluid
Changing the AT fluid
Replacing the belts
Replacing the spark plugs

All the above things seems to be pretty cheap things I could do that would go a long way to keep my car running without problems I just can't seem to find out what mileage I should do these things at. Thanks.

 

Change em as soon as u can. Sooner the better, later the more money. lol

 

You are 11k miles overdue on those items. Do them soon for longevity.

 

I just replaced the spark plugs in mine (67k on the odometer) and they def needed replacement. Oh and check your plugs to see if they have oil on them. 2 of mine were coated in oil and this seems like a common problem.

 

I'm not doubting it is a good idea to change the plugs at 60k miles, but IIRC doesn't the factory manual say to change them at 105k miles? Are platinum NGKs or standard coppers the best for the 350z?

 

Yea I am going to take your guys advice and change out my plugs and belts asap... and I will go ahead and take care of the differential fluid next time I get my oil changed... but I am a bit worried about messing with the automatic transmission fluid since I am not having any problems and according to Nissan's service site, it always shows replacing the AT fluid with an (except 350z)

I can't seem to find any guidelines on when its a good idea to have that changed

 

IMO you are overdue to change everything you mentioned (But i'm OCD).

But when it comes to Auto tranny fluid, IMO if it ain't broke, don't fix it! Everyone i know that has changes their auto tranny fuid on a relatively high miliage car, ends up having tranny issues shortly down the road. (Something to do with the fresh fluid being more viscuous, thus putting more strain on the aging internal parts of an automatic tranny).

Check the fluid, and if it doesn't smell burnt, it's not low, and you aren't having any issues, i'd just let it be. If you do decided to change it, i'd let the dealer do it so if something gets messed up, you have someone to point a finger at.

FWIW I have 143,000 miles on my DD beater Cavalier. And i towed with it for 20,000 miles of that. I have never changed the auto fluid, and have had no issues ever. Still smells clean, and have plenty in there.

 

Yes, manual states changing spark plugs at 105k miles and I would stick with OEM (NGK) platinum plugs.

 

I read somewhere that 350z new automatic transmission fluid don't have to be changed. That they are meant to last the life of the car. It only needs to be checked every now and then to make sure they are at the right levels. I heard it had to do with something about a change in the way the transmission is built. I could be wrong. I'm doing investigation myself because my 60k is coming right around the corner.

 

I haven't heard this, but some people say not to change the fluid unless it's burnt due to theories about flushing the fluid dislodging metal particles or the new fluid adding enough pressure to damage a high mileage transmission that would have done fine for a while longer with the old fluid.