[ZAZ]

Hi, I just went through same concerns having purchased a six year old 86 with an odd reading of just 4300 km or under 2000 miles.
I made a decision to drop all fluids.
Brake fluid clutch fluid.
Then under floor.
Removed skid pans and dust straw and debris stones and stuff.
Then drained all the oils ......
The sump oil ran out like black sooty water.
The differential oil glugged out like green slime.
The gearbox almost as bad.
I found grey sludge on both the magnetic drain plugs in diff and gearbox.
I flushed out the oils.
Replaced with correct gl grades.

Now the jury is out on oil for engine.

I spoke with wrx sti guys I spoke to repco and Atlantic reps and toyota techs.
The drivers handbooks show different oils for different handbooks in Eu ja and USA

Due to hot Australia summers on 40 c I have put in zero w 30 for a while until 5000 km and will change the oil every year.

Toyota had not serviced this vehicle or made any logbook entries.

Even though aircraft horizontally opposed enginrs like Lycoming are tractor engines they are run in on mineral oil for 100 hours before going to multi grade shell detergent oils.

Oil is cheap enginev metal is not cheap.

Let the debate roll on.