There is NO cabin filter on the 2003 Sienna.
You can register your vehicle on the TOYOTA website for FREE.
This will give you access to any open Recalls and you can also get a online version of the owner's manual.
The correct Motor oil will be a 5W-30.
It is important to use the correct viscosity due to the Varible Valve Timing (VVT) oil control system.
Mobil 1 would be a good off the shelf oil
I would NOT go for a extended OCI.
I do 5K with Redline 5W-30, but Redline is overkill.
I order it by the case, which brings the price down some.
Doing a OCI of 5K to 7.5K would be a good range.
It is SUPER critical to make sure that the PCV valve does not become clogged.
The 2003 has a metal PCV valve the screws into the rear valve cover, passenger side......kind of hard to see with the intake/throttle body in place.
A clogged PCV valve WILL lead to sludge issues.
The went from the PCV valve the pressed into a grommet to the screw in type starting in 2003.
Also, the 2003 has improved baffels inside the valve covers to reduce buildup that can block the flow of air through the crankcase......airflow which is critical in getting contaminates drawn out through the PCV valve.
Oil filter, I had a '96 FORD Windstar, that I bought in '99 with just under 37K miles on it......and got 10+ years out of it and had over 229K miles on it.....still doing very well when I sold it.
So, just for fun, I did some looking on the WIX oil filter website.....and found that the oil filter for the Windstar is a direct fit for the Sienna, just slightly longer, more media surface.....but all the other specifications match up.
The slightly longer filter fits just fine....and that is what I have been running.
I DID run AutoRX, but did not follow the directions and use a "dino" oil.
I would follow the instructions on the AutoRX website....and use one of the oils that they recommend.
I would NOT use MMO or other faster product.
My plan with the Redline oil is that it should not need any additive to keep the inside of the motor very clean.
One thing that the older sludge prone (2002 and older) 1MZFE has been reported to have happen is that the oil pump pick-up screen can become clogged.
THIS is why I (only my opinion) shy away from any faster cleaner.
Removing the oil pan can be tricky.......it IS a nice direct shot.....nothing in the way, HOWEVER, they used a RTV type sealant instead of a gasket.
What this means is that removing the pan after you remove the bolts might be more difficult as you don't want to bend the lip by prying too much.
The ONLY actual gasket that I have been able to locate is a cork gasket for the oil pan.
Valve cover gaskets, I bought the felpro rubber type on the RockAuto Website.
When I do brakes, I plan to use Raybestos "Advanced Technology" rotors and Akebono pads, or the Raybestos "Advanced Technology" pads.
If you change the spark plugs, I would use EXACTLY the part number listed....either DENSO or NGK.
They are rated for 120K miles.
Once you change the rear plugs, you will not be wanting to take a risk on a plug that may not last as long.
The transmission fluid that is correct is a fluid that meets the DEXRON III specification.
I have Redline D4 in mine, Mobil 1 is another quality fluid.
The in pan filter for the transmission is just a nylon screen.
I changed mine, using a Beck/Arnley that came with a rubber style pan gasket (better than cork).
I installed a Magnefine filter in the transmission cooler line that flows back INTO the transmission from the cooler.
A transmission fluid change interval of 30K miles is recommended if doing a fluid exchange through the cooler line, which changes more of the fluid.
If you just want to drain the pan and differential, then maybe every 10K - 15K miles.
For power steering fluid, use the SAME fluid as the transmission.
To change that, I just unclip the power steering resevoir from the inner fender and dump it into a shallow pan.....refill and run the motor to circulate the fluid....then repeat.
The correct OEM fluid is the TOYOTA RED Long Life (not the pink Super Long life).
The TOYOTA RED that I bought at the dealership is a concentrate, intended to be mixed 50/50 with distilled water.
I seem to remembe it costing about $21 with tax.
My coolant was clean, so I just did a drain & refill.
The timing belt is due for change every 90K miles.
It is a involved job that I chose to have done at a dealership for around $500, including a new water pump.
The water pump is driven by the timing belt......so I had them change it while they were right there.
I have 1 recall, for the spare tire metal part at the end of the cable.
That metal part that actually holds the spare tire can rust and break......
TOYOTA will paint it, if it is not too badly rusted, with a special paint.
Or, if it is too badly rusted, they will replace it.
ALL FOR FREE.
I had already painted mine with Eastwood Rust Converter, then with Eastwood Rust Encapulator by the time I got the recall.
NONE of the accellerator recalls apply to our 1998-2003 Sienna because they do NOT have the same system.
The accellerator pedal connects to a cable that directly connects to the throttle body.
The recalls were for certain boxes that the accellerator pedal connected to.....that told the computer the accellerator position, and then the computer controls the throttle body.
Here is a link to a folder of pictures that show much of what you are planning to do.
PLEASE NOTE that I am NOT a mechanic.....just another DIY person, so take what you see with a grain of salt.
http://rides.webshots.com/album/576572371kcnZsT
