tbutt130

I am a relatively new owner of a 2006 IS350. I was looking over the rear diff post in the faq, and I was looking at my service manual. It says to replace the rear diff oil at 60k miles if you have the limited slip diff. How do I know if I have a limited slip diff?
Thanks,
Kevin

Kurtz

iTrader: (1)

Not sure which FAQ you were reading, but per the owners manual the 2IS rear diff does not ever call for a fluid change. (and it's not a real LSD either).

tbutt130

I was reading under section 5A of the 2is faq's "DIY: how to change the differential oil in your IS350"

I copied the following from page 51 of the maintenance book in my owner's manual. I highlighted the section I was unsure about (and the notes that apply to that section.)

SCHEDULED MAINTENANCE LOG



72 Months or 60,000 Miles
• Replace engine oil and oil filter1
• Measure brake pad thickness and rotor runout
• Measure thickness of brake rotors (GS 430, IS)
• Replace brake fluid
• Replace engine air filter
• Replace spark plugs (GS 300, IS)5
• Replace transmission fluid (ES 330, LS 430)3
• Re-torque axle shaft flange bolts (all models except ES)
• Rotate tires (all models except IS with different size front and rear tires)
• Road-test vehicle
• Inspect the following:
____Axle shaft boots
____Ball joints and dust covers
____Body
____Brake lines and hoses
____Drive belts
____Engine coolant6
____Engine valve clearance (ES, GS 430, LS, SC)
____Exhaust pipes and mountings
____Front differential oil (AWD GS 300,
AWDIS250)
• Inspect nuts and bolts on chassis2
• Replace air conditioner filter
• Replace differential oil (ES 330 note3 ,
IS note4)
____Fuel lines and connections, fuel
tank band and fuel tank vapor
vent system hoses
____Fuel tank cap gasket
____Manual transmission oil (IS 250)
____Rack and pinion assembly
____Rear differential oil (IS, GS, LS, SC)
____Steering linkage and boots
____Transmission fluid (ES 330, SC)
Date: _____________________ Mileage: _______________________
Notes:

1 Reset the oil replacement reminder (“MAINT REQD”)
light after replacing engine oil, if vehicle is equipped
with this light.
2 Required only if vehicle is operated primarily in desert,
on dirt roads or while towing.
3 Required only if vehicle is operated primarily while towing.
4 If equipped with limited-slip differential.
5 Required under the terms of the Emission Control
Warranty.
6 Replace only with Genuine Toyota Super Long-Life Coolant
or similar high-quality non-silicate, non-amine, non-borate
ethylene-glycol coolant with long-life hybrid organic acid
technology (i.e., a combination of low phosphates and
organic acids).
51

Bichon

Kurtz is right on both counts. Limited slip on the IS350 is nothing more than software in the ABS controller, and the manufacturer does not call for a fluid change in the rear diff.

The reason some folks are glad they changed it is that when they removed the magnetic drain plug, they found some metal slivers adhering to it. Others argue that if the slivers are adhering to the drain plug, they aren't circulating in the oil.

Kurtz

iTrader: (1)

AFAIK the only US-Spec IS that has a real LSD is the 2010 IS-F...none of the cars usually lumped as 2IS (ie ISx50s) have one.

tbutt130

Thanks for clarifying. I was asking the dealership about the 60k service and they quoted me $1400. Seemed a little (actually a lot) steep so I asked about what they did. In addition to the plugs, oil, and brake fluid change that are in the recommended service schedule, they include the diff oil and trans oil changes. I am just trying to figure out what I need done and what they are trying to pad the bill with.

Lexiss_sc430

iTrader: (2)

If you plan on owning the car for a long time I would recommend changing out the Diff fluid every 60-75K.

edgeucated

iTrader: (4)

1400? holy crap that steep haha

tbutt130

That is steep. I am planning on keeping the car for a long time, that was a big reason behind the purchase of a Lexus. So is the general consensus to change the diff oil around 60K? How about the trans fluid?

Lexiss_sc430

iTrader: (2)

I personally change out my trans fluid every 15-20K, I choose not to flush the tranny, instead I remove one of the trans hoses that runs to the radiator and then turn the car on. the trans pump will pump out about 2-3 quarts of fluid, you will still have a few quarts in the torque converter and other misc areas but you will be able to remove 50-70% of the total fluid you have in there and replace it with fresh stuff.

Kurtz

iTrader: (1)

You do realize than on a 2IS the only thing in those hoses is radiator fluid, right?

Not very useful for transmission maintenance.


Again- read the owners manual- the transmission on the 2IS is a sealed unit and should not be changed.

(in fact, it's physically impossible to change a significant amount of the fluid- as we established in the 7-8 page thread we had on that very topic a while back).

If your dealer is offering to change your transmission fluid I suspect what he's offering to do is overcharge you to remove the drain plug on the pan, which gets only a small fraction of the total fluid out, then refill the whopping 1-1.5 quarts or so he got out that way. The people who built the car say it never needs to be changed... the people who bill you for changing it say it needs to be changed often, despite only a tiny amount of the total fluid actually getting changed by doing it. I wonder whose word to accept.


I've also yet to see a single decent explanation for what these "change your diff at X miles" folks know that the people who built the car, and say a change is never required, didn't know.

It's not like there's a real posi burning up clutch cones and dumping material into the fluid back there.



The things you actually need done at 60k miles on a 2IS:

Oil change.
Brake fluid change.
Air/cabin filter changes (do these yourself, they take 5 minutes)
Spark plugs changed.

That's it.

In general, don't ever ask a dealer for the "x miles" service... he'll increase the cost of your bill 2-3 times without doing anything extra the car actually requires. Just get the actual services done the car needs.


For a 2IS that is: (by the book)

Every 5k: oil

Every 15: air/cabin filters

Every 30: brake fluid

Every 60: spark plugs

Every 100: coolant

That's it.

Lexiss_sc430

iTrader: (2)

Hey I'm just trying to give a little insight on how I do it.
so then does the IS have a separate transmission cooler? if it does the same process can be done to those hoses, just trying to help out. Oh and I'd love to see someone go without ever changing out their trans and diff fluids, not saying it cant be done but do you think these fluids have magical ferry dust in them? These fluids are still effected my heat, which is the main enemy for oils and as they become contaminated through the years they loose their effectiveness.
If you want to own your car for a long period of time wouldn't you want to take some preventative maintenance measures?

Kurtz

iTrader: (1)

You can't change the transmission fluid on the 2IS.

The only cooling lines that run to the transmission contain coolant not transmission fluid. They run to a heat exchanger physically built into the side of the transmission.

There are no external lines containing transmission fluid.


I can literally show you a diagram if it'll help you.


And exactly how much heat do you think is going on in the rear diff of a non-posi differential?

I ask again, what do you know that the people who built the car don't?

tbutt130

Thanks for all of the good info. I was wondering about that after I actually read the maintenance schedule and saw the paragraph about the transmission being a sealed unit with lifetime fluid. The 01 mercedes I had was the same deal.

Koz

If I'm not mistaken, the rear diff comes with synthetic gear oil from the factory. I personally change all diffs/transfer case in all my vehicles at approx 5K miles to the best synthetic gear oil I can find. This will help the mpg and insure max protection since I never touch it again unless there is a leak! I found this product to be the best!

http://www.amsoil.com/storefront/svg.aspx

Koz