Oil Change Issue.

[07WYarisRS]

Redline and Amsoil are about the top 2

oils as classified in 5 groups

group I oils are the cheap junk like castrol GTX, Q state etc
group II oils are better nown as syntheitc blends as they are a mix of group I and group III oils
Group III oils are what 99% of synthetic oils are made of... These oils are synthetic oils made from mineral/crude oil. Most use the hydro cracking method and use heavy amounts of pure synthtic base stocks as additives. Group III are far better then any group I or II oil. Castrol Syntec and Mobil 1 are examples of group III synthetics.

Group IV ~ V These are the best of the best and are not actually oil. these are lubricants but called oils to not confuse the mass public...These are not pumped out of the ground, instead and made by folks in white lab coats. Most contain extremely small amounts of mineral oil or no mineral oil at all. Group IV synthetics are POA based ( Polyalphaolefin )
group V are usually Ester based synthetics

Redline and Amsoil products are bother a group IV-V synthetic and contain no mineral oil. This eliminates any mineral by products that oxidize and form sludge and engine deposits.
I should point out BOTH buy their synthetic stock from Exxon/mobil1 so you know even though the formulas are different the base stocks use in Mobil1, Amsoil and Redline are all the same.
Royal purple Racing oils are group IV-V however the regular stuff is group III...

If you can't find or afford a group IV-V synthetic... be sure to use a quality group III like Mobil 1.
My #1 choise is Amsoil, Redline is also great but far fewer products available
don't forget... the engine is just 1/2 of it... be sure to change the transmission fluid as well. 75W-90 for the Manual trans and the universal ATF for the auto's.