Oil & fluid recommendation

Any 0W-20 will do. The Prius engine is not stressed (high RPMs and temps) like other vehicles. I use Super Tech from Walmart in the 5 qt jug. I fill with 4 qt and reserve the remaining 1 qt for top off, which I've never needed to do in my 70K miles so far. 4 qt puts the oil level halfway in the dipstick range. I prefer not to overfill. I sent a sample to Blackstone labs and got a glowing report. I change at 10K miles per the manual.

Also, 21K miles is way too soon to worry about a tranny fluid change. They go well over 100K miles. It's not a real transmission anyway. There are no traditional gears or shifting. It's called the Power Split Device (PSD). You can look it up on YouTube.

 

For engine oil any oil meeting the spec will be fine. I believe Amsoil is pricey? I’d suspect it’s no better than others, or at the least overkill. Makes you feel you’re pampering your car?

Toyota cautions against using anything but Toyota ATF WS in the transaxle; warns anything else may damage it.

There’s a link in my signature regarding 3rd gen transaxle fluid change, mostly applicable, but check attached as well. Main diff is drain and fill bolt torque, a bit higher (no clue why). If you’re on a phone turn it landscape to see signature.

My 2 cents: an early transaxle fluid change is worthwhile, and then stretching the interval is ok as well. Just my impression, judging by drained oil darkening, with the several changes I did on our gen 3.

 

Toyota 0w-16, and no trans change until 30-40 k, with Toyota WS fluid. Prius prime 2020 with about 19,600 miles.

 

These are relatively low compression, low-RPM engines. And because they are in hybrid drivetrains, they aren't even "on" as much as most gas engines.

You can spend all you want but these things run zillions of miles on cheap brand x motor oils.

Transmission is a different story, sort of. Little point in changing it before 100k as there are no clutches, drum/band assemblies or the like to shed particulate contamination into the ATF. No torque converter to shear or thrash it.

However there are insulated electric motor windings, and you want something that will not eat that electrical insulation. Worth the $ for the real Toyota WS fluid because of this.

 

I believe the 2019 Prius motors calls for 0w16 motor oil, check the manual and oil filler cap. Normally running 0w20, specs changed that model year. That being said, 0w20 should be fine - as Leadfoot stated, they aren't a particularly hard working engine - less so in a Prime, spending most of it's time in EV mode - like mine. I too use the cheap Wally Super-Tech, but spring for the 20K mile full synthetic. Additional anti-corrosion and anti-wear formulation. I've calculated that I would have 7500 actual ICE mileage on my car, if I move to annual oil changes - rather than rely on the 10K mile odometer oil changes. If the oil gets too dark; I may reconsider.
My personnel preference is to do an early ATF change. In my experience the ATF is darkest and dirtiest on it's first change. Subsequent changes come out cleaner - even with 80K to 100K miles on her. If your expecting the transmission to last, I'd stick with the recommended Toyota WS ATF. These transmissions aren't prone to failures, so why mess with the Amsoil stuff? The OEM builders of these transmissions expect Toyota WS ATF to be used in their product, why take a chance on marketing hype.

Hope this helps...

 

Amsoil's products are excellent, exceeded only by their marketing. Really, any 0W-16 oil, if that's the Toyota recommendation, or any 0W-20, if that's acceptable to Toyota, will be great. All of the 0W- oils are synthetic, so buy any brand you trust. Two things to keep in mind about these cars---
---The engines in most of ours are very lightly used. There is no indicator about actual engine usage. The 10,000 mile oil change interval does not account for electric miles, so no one knows actually how much the engine runs in this interval.
---The transmission is different. It has no clutches that shed particles. It is purely a gearbox. Yes, gearbox oil may need changing, but the intervals are very long. Since we don't know better, it is best to stick with the Toyota product, their WS (world spec) ATF. (In my 32 year career with industrial gearboxes up to 60,000 hp the oil was changed only if external contamination occurred.)

I just looked up the Amsoil recommendations for oil for my Mazda. Four choices of Amsoil 5W-30 oil for that engine. Overkill. I'll stick with my favorite, Pennzoil Ultra Platinum (which itself is overkill even for this turbocharged engine).