diff fluids and engine oil for 2018 artic cat

[toys]

HI all.my neighbour asked me to do some maintenance on their artic cat atv's.
#1 is a 2018 alterra 500 cc
#2 is a 2018 alterra vlx 700cc
they brought me oil and filters but I don't think they gave me the correct stuff.
I downloaded the service/owners manuals and diff. fluid should be hypoid 80w90 and engine oil 0w40.
they got me sae 80 diff. oil and castrol 0w40 engine oil.
do these things have wet clutches and I doubt sae 80 is going to work when 80w90 should be used.
I'm thinking i'll use amsoil 75w90 for the diffs. and rotella t6 5w40 for the engine,
Any input?Thanks in advance.

p.s. i've got a trx300 fourtrax and I use 75w90 in diffs. and 5w40 rotella in the engine and transfer case.

 

[dnewton3]

Regarding the diffs, does the manual spec a GL-5? That would be far more important than the grade; make sure it's a hypoid gear oil if that's what it calls for.

As for the engine oil ... again, what is the spec? API SL? SM? If the oil they gave you meets/exceeds what is required, either would work, so why not use what they provide?