Synthetic Oil: Is is REQUIRED?

Another thing, so often left out of the discussion, is that the Warranty and Maintenance guide does not say you can go 10,000 miles or 1 year on 0W-20.

It says you can do that if your driving conditions are not 'special'. It also describes several things that count as 'special' operating conditions. They don't send the Toyota Police around to check on your driving; you're on your honor to decide if you're in the special conditions or not (I am, for example), and if you are, your interval is 5000 miles / 6 months, right there in black and white in the Guide.

 

Hope I don't get my right posterior gluteus maximus chewed on because I am going to add simple stuff, simple stuff to this overly chewed on point of maintenance..

WHY, knowing that SYNTHETIC is mechanically superior to organic oils, would someone who is "OCD" about their PRIUS, ever consider using mineral lubricants ?
SAMPLE and FACT: Old type mineral oil/lubricants break down AND absorb MOISTURE, that IS one of the major damaging factors of metals, NO ?
CORROSION...

USE SN or SP or what the NEXT API description letter in the alphabet for the oil BECAUSE for some reason(improvement), IT IS BETTER than the one previous.

THANKS !
(I'm out of breath...)
BTW, my 2020 has 225K now...

 

It just comes down to context across time. If a Prius owner is reading their pre-2004 manual, it may suggest a type of oil that is available in either refined mineral or fully synthetic form.

Your 2020, on the other hand was built recently enough that the 0W oils recommended for it are not able to be be produced through petroleum refining- they must be synthesized from base stocks.

Refined petroleum may not be mechanically superior to synthetics, but it is usually economically superior. And if it is mechanically good enough, why not? Again, it is only a question for models older than yours.

 

Your 2020 Prius calls for 0w16, only available in synthetics, I guess if you look hard enough, you can get it in Semi Synthetic. And 0w16 is actually SP. There's no 0w16 SN or SN+. In fact, there was a brief moment when 0w16 oil was available before the API certified it.

 

Just going to point out that based on the attached photo of the owners manual, synthetic is not required nor is 0w-20 and all of the above posts are wrong. It is however ''recommended''. The only ''requirement'', as clearly stated in the photo, is that the oil is an ILSAC-GF5 multi grade oil. In a country as litigious as the US, I guarantee you that the lawyers were very careful in selecting the words recommended vs required, and made sure Toyota used them appropriately. They mean completely different things in a court room and it is surprising so few people pick up on this. Now, I am not saying to go against what Toyota recommends, but, in other countries where CAFE requirements are not as strict, your exact engine is specifically allowed to use at least up to a 5w-30 API SN oil and I have seen owners manuals where that allowance is not even based on outside temp, it is simply allowed. So no, your car does not ''require'' synthetic or 0w-20. Also keep in mind that the MPG of your car was certified using 0w-20 oil, so if toyota was too blatant/clear about allowing a thicker oil, they would have to put up with a class action lawsuit over reduced mpg than advertised, so they make you think you ''have to'' have a 0w-20 when you don't. Your engine will be fine on 5w-20 conventional oil assuming you change it when it needs to be changed and the cold viscosity is acceptable where you live.

 

I would not use conventional 5w-20 for a 10k oil change.

 

I would not recommend that either, but that is slightly besides the point. Point is, a 0w-20 is not ''required'' nor is synthetic so for example a 5w-30 is allowed. On a side note, my 1986 corolla owners manual called for 10K oil change intervals.