I have a 2006 IS350 with 158k KM (98K miles) and when I purchased it 5 months back, the previous owner wasn't sure if the differential fluid had ever been changed. Although this concerned me, I still went ahead and bought it since the car was in excellent condition for the age, and since 2IS 350s are extremely hard to find where I am in Canada. So far, I've done a drain and fill for the transmission but now I'm looking into changing the diff fluid too. With the diff fluid potentially being original, would it be a bad idea to change it? Just wondering because if people say not to change tranny fluid if it's very old (cause of the fluid holding a lot of friction material), wouldn't it be similar for differentials too? If I were to change it, how many litres come out realistically? The manual says to use 1.35L (1.42qt) of Toyota Genuine Differential Gear Oil LT 75-85 GL-5, Toyota Genuine Synthetic Gear Oil or equivalent.

 

Its fine to change it. Good rule of thumb is to fill it until it comes out of the fill port (which is about 1.5 qts). Make sure you replace BOTH crush washers. Read the DIY for it. I’ve done mine twice, first time with Mobil1, second time with Amsoil.

https://www.clublexus.com/forums/is-...ispreloading=1

 

I used Amsoil synthetic Heavy duty gear oil when changing my rear Differential fluid. Works great, really smoothed things out

 

The rear differential is just a cluster of metal gears. Change away!

 

I just changed mine, it's not that hard and you would be surprised at how dirty that magnet gets. Here is a vid, and if you look at the video take a look at the magnet, its amazing how much stuff was collected on it.

 

The reason people say don't change automatic transmission fluid is this. In the pre 80's, fluid technology was not what it is today and the fluid would varnish. Inside the trans there are steel and Teflon slip rings that allow drums with clutch packs to spin and have oil pressure applied.
As oil aged and parts wear, internal leaks at those slip rings had a couple things happening. Some leaks allowed clutches to burn as leaks dropped the pressure and clutch packs slipped and burned. Other cases the oil turned to varnish and built up like plaque in an artery plugging some leaks.

When new replacement fluid which is high in detergent was added, it disolved the varnish, created an internal leaks, and the transmission failed as the clutches slipped and it burned up.

With Newer technology fluid, it doesn't turn to varnish so rarely does a fluid change cause a failure that wasn't in play already.

The rear diff doesn't rely on pressurized oil to make it function. The risk of fluid change causing a failure is zero!

That's said, there can always be a surprise. Like this from a used 350 I bought... The magnet isn't furry with metal, but this was left in it during the build and came out during its first oil change at 90,000 miles.
Best guess is the moment the diff started spinning, the magnet caught this drilling chip and it remained there on the magnet until I drained it.

 

whats a good interval for diff fluid changes?

100,000 km?

 

My maintenance schedule recommends every 64,000KM or 48 months for the diff fluid.

 

For the IS250/350 RWD (US Manual) it does not list fluid change intervals, only for ISF. I did mine anyway at 54K miles, changed it to Amsoil Severe Gear 75W-90

 

Different countries with their different requirements. I figure most of Canada would sort of be considered a "heavy duty" area as well due to the weather, so probably another reason most of the stuff that's ignored in the US manual is listed in the Canadian one. If I had to decide between a maintenance plan though, I would obviously go with the Canadian one for longevity's sake.

 

USED Red Line Fully Synthetic 75W90 GL-5 gear Oil part 57904 (Red Line states the 75W95 doesn't any additional protection over the 75W85 GL-5, but the 75W85 may offer very minor gas mileage benefit. Produced to satisfy vehicles requiring use of a 75W95 fluid)
https://www.redlineoil.com/75w90-gl-5-gear-oil
API Service Class GL 5+
Vis @ 100°C, CSt 16
Vis @ 40°C, CSt 112
Viscosity Index 155
Pour Point, °C -45
Pour Point, °F -49
Brookfield Viscosity, Poise 1100 @-40°C

Red Line Fully Synthetic 75W85 GL-5 Gear Oil part 50104
https://www.redlineoil.com/75w85-gl-5-gear-oil
-API Service Class GL 5+
-Vis @ 100°C, cSt 11.5
-Vis @ 40°C, cSt 68
-Viscosity Index 163
-Pour Point, °C -45
-Pour Point, °F -49
-Brookfield Viscosity, Poise 300 @ -40°C

 

About to perform differential fluid change, (Lexus IS 350 - 1.35L), and wanted to confirm if TOYOTA OEM GL-5 75W-85 (Part 08885-02506) is fully synthetic. Back of can states "using synthetic technology". Unsure if can has since been updated and may no longer states this. Also located part TOYOTA 00289-75140 - SAE 75W-140 DIFFERENTIAL GEAR OIL FULLY SYNTHETIC. Unsure what vehicle / transmission would require it.

 

I can only guess if its a true synthetic, but its what's recommend. That's what I put in mine.

 

I believe it may not be a full synthetic . Have some additional information with regard to the 75W 140 full synthetic differential gear oil;

Most modern oils are multirate oils, specified by two numbers, one for the oil at room temperature and one for operating (higher) temperature. The first number in "75W140" indicates the oil will be no thicker than a single rate 75W oil when at room temperature. The second number in '"140", indicates that the same oil will be no thinner than a 140W single rate oil at operating temperature. So, the difference between 75W90 and 75W140 is that at operating temperature, the 75W140 will be considerably thicker than the 75W90, but at room temperature they will be about the same viscosity..

 

Would a member be able to confirm if the Rear Differential Filler Plug & Drain Plug are the same part / part number or different (90341-18032Rear Differential Filler Plug)