So, I recently talked to my mechanic. Hes an older man, and has been working on cars his whole life. He said you should not change your differential or tranny fluids unless its giving you problems, just make sure theyre not leaking or low. He said it sometimes ends up creating problems. Ive always gone by the book on this and my car having 100k+ miles was going to change both until he made me second guess myself. Looking into this I have seen that some people beleive that in cars with higher mileage, specifically in the tranny, its better to keep the current fluid as its used to operating with a certain amount of friction. Anybody want to throw in there $.02 on this?

 

Urban myth, change it. What you may want to avoid is a flush. A drain and fill will do you no harm. The tranny holds about 10 quarts. A drain and fill will only get about four qts out. Drive a few thousand miles and do it again till you get new fluid throughout the system. I believe the problem with a flush with high miles is the pressure of fluid they send thorough the tranny to "flush" it. There may be weak seals or metal shavings that end up in the wrong place.

 

Check the transmission dipstick and wipe it on a white napkin. The color should give you an idea of the condition old the fluid. New, it's a pinkish red and if it's burnt it'll be dark brown.

 

I agree with your mechanic. I've owned many many vehicles and have never changed differential or transmission fluids even on vehicles that I put on 200k miles.

Never try to fix anything that isn't broke.

Telcoman

 

The job of transmission/diff fluid is to keep the moving components lubricated and cooled. New, fresh fluid does a better job at both tasks than 15 year old used up fluid, which may or may not also have metal particles floating around in it from normal wear and tear, accelerating the process even more.
We change engine oil for this same reason, although it is subjected to much tougher conditions than most other automotive fluids.

Of course, changing 15 year old fluid with a new fluid of a different weight or type than what was designed for the car obviously can cause problems, and the "if it ain't broke don't fix it" adage certainly applies as old fluid isn't something that will usually lead to catastrophic damage, just theoretically accelerated wear over time.

I choose to change all my fluids on purchase (of a used car of course) and at least every 100k miles, for peace of mind more than anything else - it's the feeling of knowing for certain your vehicle is properly lubricated and all moving components are ready for whatever abuse I feel like dishing out for the day.

It's not like refilling every fluid in your car costs more than $100 and takes more than 3 or 4 hours - and the process of changing them gives you a good chance to inspect everything under the car and see how much internal wear some of the parts have (based on fluid color, metal shavings...)

 

Don't you also run 87 octane? Man, you like to go against the books

 

Hey, if it works, I'm not complaining. My G needed trans fluid drain and fill, diff fluid drain and fill, and premium gas in its 130k Miles so far.

 

I personally felt a difference after putting in new fluid. I've also not had a problem with the tiptronic shifting since I did a drain and fill. Before it would only work for a short time before shifting itself back in D. Not sure if the two are connected, but maintenance is maintenance

 

Yes I do!

I've saved thousands of dollars over many years by not believing the BS being peddled to scare automobile owners to spend, spend, spend lots of money on a vehicle that they most likely will no longer own in a few years.

On my previous 06 G35 6 speed manual that I traded in at 171796 miles I never changed the differential or transmission fluid and used regular 87 octane. It did have a small differential fluid leak and needed brakes, and a headlight ballast when I decided to trade it in for my present 2012 G37S. The dealer most likely sent the vehicle to auction and those problems belonged to the second owner.

When the time comes that any problems that crop up with my current G37S I'll just replace it with another new vehicle that comes with all new parts and a warranty.

I can do that with the thousands of dollars that I've saved every year.

FWIW the only money that I've spent on my current G37S this far were for 25 oil changes, (air and cabin filter replacements that I do myself), one battery replacement and two tire replacements with alignments. All work done at the dealer.

Telcoman

 

Who's scaring automobile owners? If infiniti engineers thought the car should run on at least 91 octane, I'm assuming there's a reason. Infiniti doesn't benefit from you spending more on gas. Not saying that you're doing any harm to your car, but there has to be a reason. Imagine you experience engine problems under warranty and they see that you're running the wrong octane. Wouldn't they put the blame on you?

 

The reason is to comply with EPA numbers on the vehicle sticker.

No because first of all new vehicles are delivered to the customer with a full tank of regular.
Service advisor and dealer mechanics all confirm using regular 87 octane is fine and its use will not void a warranty.

Have you ever heard of anyone running a lab test on a full tank of gas upon delivery to a customer to confirm the octane of the delivered fuel in the tank?

I would advise you to use premium gasoline and change all your fluids monthly

You'll sleep better at night.

Telcoman

 

At 70k miles my rear wheels were actually hard to spin with the car in the air, trans in neutral. After replacing diff and trans fluids, it spun like butter. Fluids wear down over time and should be replaced.

For auto trans, do a drain and fill. Most shops these days suggest against a flush. I honestly have a hard time trusting a mechanic who seems "stuck" in old processes and recommendations. Kinda like people who buy modern synthetic oil and still change it at 3k miles.

Owners like telcoman are why I promptly replace all fluids and do a tune up on any used car I buy. Never know if the previous owner had that "it's the next guys problem" mentality.

Oh, my last Infiniti had 256,000 miles on it, still running good when I sold it. My current 06 has 248k and the only thing major was replacing a lot of worn suspension components at 200k. Stock clutch even lasted until about 220k. I contribute this to actually performing preventative maintenance on all my vehicles. This reminds me, my Armada is due for trans and diff fluid changes, it's at 120k, last time I did all that was around 55k, so I'm behind.

 

I'll do as the service manual recommends, designed by the engineers of these beautiful engines. Thanks
Not saying you'll have problems running regular. That is, if you're knock sensors are working properly. If those fail, you're screwed. I would never run regular for long periods of time. Looking through the FSM, I didn't see that premium is REQUIRED, but it does state that vehicle performance will be impacted. I'll leave it here:
Precautions for Fuel (Unleaded Premium Gasoline Required) NAS0005S
Use unleaded premium gasoline with an octane rating of at least 91 AKI (Anti-Knock Index) number (Research
octane number 96).
If unleaded premium gasoline is not available, unleaded regular gasoline with an octane rating of at least 87 AKI number (Research octane number 91) can be used, but only under the following precautions:
● have the fuel tank filled only partially with unleaded regular gasoline, and fill up with unleaded premium
gasoline as soon as possible.
● avoid full throttle driving and abrupt acceleration.
However, for maximum vehicle performance, the use of unleaded premium gasoline is recommended.
CAUTION:
Do not use leaded gasoline. Using leaded gasoline will damage the three way catalyst. Do not use E-85
fuel (85% fuel ethanol, 15% unleaded gasoline) unless the vehicle is specifically designed for E-85 fuel
(i.e. Flexible Fuel Vehicle - FFV models). Using a fuel other than that specified could adversely affect
the emission control devices and systems, and could also affect the warranty coverage validity

 

If the transmission wasn't meant to be flushed the manufacturer would have made the required 30k service interval. It's a widely perpetuated lie/myth that you aren't suppose to change the fluid. If I have time I'll dig up my short story about it.

 

I'm pretty sure nissan sent out a TSB about not doing a full flush. I saw it around hear long ago. Maybe it was only if the service has been neglected for so long