Hi all, and welcome to the best Toyota forum out there. As you can imagine, we see a lot of cyclical posts, so thought I'd capture a few main topics in one post.
Oil (weight, brand, interval, filter)
Fahgedaboutit. Go to a religious forum and talk about beliefs, you'll get the same content. Do what your manufacturer says (generally) and don't think you (or anyone else posting here) is an expert because you/they read a post somewhere. An extra quart won't destroy your engine. Switching from 5-30 to 5-20 or 0-20 won't destroy your engine. Change it around 5,000 miles as a minimum (if this is not a 70s/80s or earlier car) and you will be fine. Your owner's manual tells you what Toyota recommends - follow that and you will be fine. Check it often, don't let it get low. Pick a filter you like, change brands if it does not work out. Mobil 1, Penzoil, Castrol - none of them will destroy your engine. Find your comfort zone, live there. Don't have an owner's manual? Look it up on the interwebs, they tend to be free.
Transmission Fluid
You'd think the oil threads are bad. My God.
- There is no such thing as "lifetime" fluid
- Toyota does not manufacture transmission fluid (or oil for that matter)
- Change it before it goes bad - check it like any other fluid
- It will fail, it is not magic fluid, so keep on top of it
- If you buy an older car with unknown service history, either swap the fluid or don't. It's your car, you get to replace the transmission if it fails
Cold Air Intake (CAI)
Captain Obvious moment: an intake filter will not make your 4 cylinder a drag racer. CAIs look cool. Buy it if you want your engine compartment to look cool.
ALL intakes are cold air, hence the point of trying to locate the scoop that intakes the air a bit away from the engine. And, by the way, the throttle body pipes hot coolant in to warm the air a bit AFTER that neat intake filter, so, yeah. Your intake system is designed by engineers for the engine. It is not likely altering the intake will DESTROY your engine, but it is also not likely it will do much for you other than look and/or sound "cool". Aftermarket CAIs are a great way to spend some extra money. If you got extra and can't figure out how to send any of that to me, then knock yourself out on that wild looking CAI mod. Yay.
Tires
There is no "best". Your roads are not my roads, nor most other people that frequent here. Your weather is not my weather ( etc.) Buy the tires that work for your car, your roads, your weather. If they don't work out, don't buy them again - buy a different brand.
Brake Pads
See Tires. If you race, get the rotors and pads to suit. If you are like all the rest of us, just get pads that work for you and your budget. If they suck, buy a different brand the next time. Buy what is recommended for your vehicle, avoid the cheapest out there as, well, you get what you pay for. I rather like stopping when I need to, so pads are not where I try to pinch a penny.
Gas (Octane)
Your engine is designed with a specific octane requirement. Most general cars only need "regular", or the lowest rated octane. Increasing this is not a magical way to gain MPGs; in fact boosting the octane has little if any impact on mileage. Engine "knock", also known as pre-ignition or pre-combustion, may be addressed by hiking the octane to the next rating (mid or even supreme grades). Higher performance engines need higher rated octane. Do yourself a favor and search "octane" on the Googles to learn more. If the compression of your engine is such that you are experiencing knock, then it is time to up the octane rating. If you are not having knock issues, then jumping to that 91 octane may address that but is not going to make you a drag racer or add 3 MPGs to your cruise. If you don't need it, you will be a good consumer and the gas station owner will thank you (not really) for the extra cash in their till, but asides from that you are getting bupkis when you select 91 at the pump. Generally speaking.
FSM (Field Service Manual, aka Repair Manual)
If you want THE info to work on your Toyota, go here:
https://techinfo.toyota.com/techInf..._US&resource_url=https://techinfo.toyota.com/ It is the complete info for your vehicle, including wire diagrams. You get 48 hours access to download everything to your heart's content. Do it, and you will be set for the life of the vehicle.
Caveat Emptor
A portion of the folks here have been mechanics for decades. A portion of the folks here can spell 'mechanic'. A few can't. Ask away, check the info, do what you think is right. Always remember a complete fix is only a tow away, so have a Nike moment and Just Do It. And post your successes and lessons learned for all to to read!