The Truth About Cars » sealed for life The Truth About Cars is dedicated to providing candid, unbiased automobile reviews and the latest in auto industry news. Thu, 17 Jul 2014 13:26:26 +0000 en-US hourly 1 The Truth About Cars is dedicated to providing candid, unbiased automobile reviews and the latest in auto industry news. The Truth About Cars no The Truth About Cars (The Truth About Cars) 2006-2009 The Truth About Cars The Truth About Cars is dedicated to providing candid, unbiased automobile reviews and the latest in auto industry news. The Truth About Cars » sealed for life Piston Slap: Sealed for an Infinite Life? Mon, 14 Oct 2013 12:11:58 +0000 Jerry writes:


Thank you and the rest of the TTAC staff for providing the community with an entertaining and genuinely informative automotive website. I’m a long-time reader, and hope you can answer some questions I had about my wife’s 2009 G37 S 7AT.

We purchased the car new in 2009 and love it. It’s paid off and we see no reason to replace it anytime in the foreseeable future. It’s a keeper.

We carpool and thus only have accumulated 29,xxx miles in the years we’ve owned it. I try to be diligent with my vehicle servicing, and prefer to do my own maintenance. When preparing for the upcoming 30,000 mile service, I noticed something peculiar in the maintenance schedule provided by Infiniti:

‘Replace automatic transmission fluid(except 7 speed automatic transmission).’

Even more curious, the 7 speed automatic is not recommended for servicing at any point in the published maintenance schedule (which terminates at 120,000 miles). I’ve always thought 30,000-40,000 mile transmission services were optimal. There is no dip-stick, which I know is becoming more typical of luxury cars, so I can’t visually assess the condition of the fluid. Visiting some Infiniti forums reveals the transmission is effectively sealed to shade tree mechanics, and requires a visit to the dealership if you’re inclined to have it serviced.

I’d love your insight. I know there is no such thing as transmission fluid that never needs changed. I know any dealership I call will disagree with the literature and recommend it needs changed as frequently as I can afford it(~$350 for a flush and fill at the local dealership). What I don’t know is: When does this fluid really need changed, and why is Infiniti keeping it a secret?

Sajeev answers:

The 7-speed Infiniti angle adds a new twist to one of the quandaries that’s been around since the early days of the Piston Slap series.  My first recollection of these “sealed for life” automatic transmissions was the 1997 Chevy Malibu, and the universal truth hasn’t really changed: change the ATF at regular intervals (being vague for a reason) and make sure to use the correct fluid.

Why be vague? Because while most folks wouldn’t go past 100k-150k on transmission fluid if they knew the benefits–and if they kept a car that long–the actual life of transmission fluid varies by owner. If you carry/tow heavy loads in a minivan that idles in traffic to and from school/work in brutally hot weather, consider a more aggressive ATF replacement schedule.  But if you are one person traveling mostly rural highways in cooler parts of the country, you may never need to change the fluid at all.  (slight exaggeration)

So what’s the right move for you?

The path of least resistance is to visit the dealer and have them do the deed, perhaps every 75k or 100k.  Which isn’t a bad idea, and considering your low mileage…when will you reach 100,000 miles? So don’t sweat it!

Send your queries to Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.

]]> 59
Piston Slap: Dreading “The Dreaded” ATF Flush? Wed, 03 Aug 2011 15:04:54 +0000

Jackson writes:

I own a 2001 Nissan Maxima and a 2006 Corvette, both purchased new w/cash. I know the Maxima with 105,000+ miles has had two ATF services, which included the “dreaded ATF Flush”. So far the thing keeps running, only issue (unrelated) was a Cat replacement (99,000) and 3 O2 sensors around the same time.

The 2006 Corvette at 5 years and 42,600 miles is due for a coolant service and I see that the ATF service is 50,000 (harsh) or 100,000 (normal). So far expenses have been limited to gas, once a year oil changes and a set of tires at 26,000 due to some aggressive driving, aggressive factory camber settings and a shard of metal. It’s been spotless so far besides a squeaky roof panel which has been solved by periodic application of Super Lube to some contact points. Should I do an ATF flush for the vette? It would be a BG machine. It’s a warm weather commuter for me (42 miles round trip per day of which 26 is highway miles on which avg. speed 75 mph which is just 3 days a week).

I have taken it on 6 long trips over the years as well as weekend cruises. I do use the paddles about 30% of the time, but do not really hoon it so much the past 2 years after getting 3 speeding tickets in 6 month period…which I fought and is another subject. So please advise.

Sajeev answers:

The easier of the two to E-diagnose is the ‘vette. First, I really hope you ditch(ed) those run flat tires for some donuts befitting a Porsche 911, as that is what the Corvette deserved from the factory. And like much like Motor Trend’s game changing car of the year, the 1997 Chevy Malibu, the C6 Corvette comes with a sealed-for-life transmission. Which begs the question, where did you hear about a 50,000 mile service interval under any condition? Not that owner’s manuals are always right, but I seriously doubt you read that from your glovebox.

These gearboxes normally go 100,000-ish miles before servicing, and your driving habits are definitely within that realm. If you have the motivation, check the fluid’s condition using the link’s info. Odds are the ATF is fine, it should have a pink color with a slightly sweet smell. If it has black-ish bits and smells like a BBQ pit, change it according to factory procedures…and good luck with that!

Now about the Maxima: I question if an “ATF flush” is really something to dread. I’d be quite thrilled with your vehicle, if I were to buy it from you. The biggest plus in the flush’s favor is how it blows out all the old fluid from the torque convertor, which is essentially impossible in vehicles without a drain plug on said convertor’s case. While it doesn’t change the transmission filter, I’ve been told by several techs that this filter isn’t exactly that high tolerance in its filtering capability. Which implies…

…that doing the “dreaded ATF flush” when your fluid degrades essentially makes the transmission filter a lifetime service part. My thoughts are completely debunked over here, but I see their opinion as more applicable to car with more advanced transmission failures.

What say you, Best and Brightest?

Send your queries to Spare no details and ask for a speedy resolution if you’re in a hurry.

]]> 17