diff mineral oil instead of synthetic/ maintenance schedule

[datboi]

so i went to the auto parts store to buy some 80w90 synthetic diff and transfer case oil

guy sold me some mineral oil, i went back and asked him to change it to synthetic, he gave me some other 75w90 oil and told me it's synthetic.

there is no info on the package itself, and i wasn't able to find info online on whether it's syn or mineral but i'm pretty sure it's mineral oil.

the car has 200.000km and likely never had a diff oil change, always driven slow and such so the oil wasn't even as dark as i expected.

will the mineral oil be an issue? how often should the diff and transfer case oils be changed anyways?

also, so far this is what i've changed, engine oil and filter, CTV oil and filter, diff and trans case, spark plugs, and coolant. is there anything else that needs to be done at 200.000km?

maybe valves? or can i wait for that?

does the car have clutch fluid? what is the maintenance schedule on that?

what about steering fluid?

also i'm ignorant so educate me please, do 4wd models like mine have front differential oil? or does the transfer case act as a front diff? i'm a motorcycle guy sorry...

[philip42h]

2 hours ago, datboi said:

so i went to the auto parts store to buy some 80w90 synthetic diff and transfer case oil

guy sold me some mineral oil, i went back and asked him to change it to synthetic, he gave me some other 75w90 oil and told me it's synthetic.

there is no info on the package itself, and i wasn't able to find info online on whether it's syn or mineral but i'm pretty sure it's mineral oil.

I'm pretty sure that it doesn't matter a jot whether it is a synthetic or a mineral oil. What does matter is that it exactly matches the specification given by Toyota for your vehicle ...

[datboi]

45 minutes ago, philip42h said:

I'm pretty sure that it doesn't matter a jot whether it is a synthetic or a mineral oil. What does matter is that it exactly matches the specification given by Toyota for your vehicle ...

as far as engine oil go, mineral oil tend to last much less than synthetic, i'm guessing this is the same for the diff?

[TonyHSD]

This where and how usually the problems with cars begin. 
Firstly there is a huge difference between synthetic and mineral oil and how these two work and protect the components especially under certain conditions like high heat, extra load, and other more severe applications. Secondly the type and viscosity were given wrong and outside the specs which makes the things even worse. 
The car care nut last video , although this guy is a real treasure and has tons of experience he got it totally wrong on two of his advices, one was that synthetic vs mineral, and secondly the fuel premium vs regular. 
In the OP case, if me I would buy original Toyota oil from established dealer and change again to ,ale sure the oil is exact specs, type, viscosity etc so I know there aren’t any chances of wrecking my car because of wrong oil filled in, which is one of the most common reasons why many transmissions and differentials goes prematurely. 

[datboi]

1 hour ago, TonyHSD said:

This where and how usually the problems with cars begin. 
Firstly there is a huge difference between synthetic and mineral oil and how these two work and protect the components especially under certain conditions like high heat, extra load, and other more severe applications. Secondly the type and viscosity were given wrong and outside the specs which makes the things even worse. 
The car care nut last video , although this guy is a real treasure and has tons of experience he got it totally wrong on two of his advices, one was that synthetic vs mineral, and secondly the fuel premium vs regular. 
In the OP case, if me I would buy original Toyota oil from established dealer and change again to ,ale sure the oil is exact specs, type, viscosity etc so I know there aren’t any chances of wrecking my car because of wrong oil filled in, which is one of the most common reasons why many transmissions and differentials goes prematurely. 

oil grade depends on where you live. you can use 75w90 80w90 or 85w90. someone living in Iceland probably should use 75w90, someone living in a hot climate like me, where temps never get below -10, 80w90 or 85w90 is ideal... 

about the toyota dealership, they only have 85w90, which is rated for up to -10 which would be an issue in a cold winter.

[datboi]

has anyone tried using mineral in their diff here? that is assuming the oil i put in it is mineral, as it doesn't specify it on the package or website

[datboi]

On 9/5/2023 at 12:56 PM, philip42h said:

I'm pretty sure that it doesn't matter a jot whether it is a synthetic or a mineral oil. What does matter is that it exactly matches the specification given by Toyota for your vehicle ...

about the weight, i called toyota and they say 75w85

a sticker on the trans case and differential says 85w90

and it say's 80w90... which is the correct weight?