Do a search for "oil leaks" in this forum.
Common locations for oil leaks in the 1FZFE:
OIl pump cover gasket (formed O-ring). Often misdiagnosed as a front crank seal leak (although you replace seal at the same time as the oil pump cover gasket)
Valve cover gasket
Spark plug tube seals (replace at the same time as the valve cover gasket)
Distributor O-ring
Upper oil pan rear arch area (often misdiagnosed as a rear crank seal leak which is relatively uncommon in relation to all the other leak sources.
Oil level sensor gasket (small seep is common, easy to replace)
Timing Chain cover (not very common and generally a small seep). Often not worth the effort/cost unless you're also
removing the upper oil pan and/or replacing the head gasket IMO.
The most common cause of oil usage/burning in this engine, generally, is from worn/old Valve Stem seals which harden and crack with age/high miles.
The Valve Stem Seals can be replaced with the head on the vehicle but often people will go ahead and pull the head to replace
the head gasket and rebuild/machine the head/valves as needed at the same time. And then you may also want to replace
the timing chain, sprockets, and timing chain slippers, replace a few gaskets and reseal the timing chain cover. And then there's about two dozen other small repairs/replacements/services that can be done while it's all apart.
That is why it helps to find someone who has worked on this engine (1FZFE) before, not just once 8 years ago, best if you can find a shop/mechanic
who has worked on the model/engine regularly.
Using a heavier weight engine oil (15W-40) can often slow down the burning/loss of oil a bit (DELO 400 XSP 15W-40 is one choice IME).
Be sure to always use a quality oil filter, Toyota oil filters are probably the safest choice if following OEM (shorter) drain intervals. IME the large size Mobil 1 Extended Performance oil filter (M301A) does well (IME based on Engine oil analyses). Other people have their own favorite oil/oil filters. Point is, avoid cheapo filters.
