Kia Optima 2017 Owner's Manual page 615

No. ITEM
*6 Fuel additives (Gasoline)
*7 Fuel filter cartridge (Diesel)
*8 Manual transaxle fluid
*9 Valve clearance
*10 Spark plug
Kia recommends that you use unleaded gasoline which has an octane rating
of RON (Research Octane Number) 95 / AKI (Antiknock Index) 91 or higher
(for Europe) or Octane Rating of RON (Research Octane Number) 91 / AKI
(Antiknock Index) 87 or higher (except Europe).
For customers who do not use good quality gasolines including fuel additives
regularly, and have problems starting or the engine does not run smoothly,
one bottle of additives added to the fuel tank at every 15,000 km
(10,000 miles) (for Europe)/10,000 km (6,500 miles) (except Europe). Addi‐
tives are available from your authorized Kia dealer along with information on
how to use them. Do not mix other additives.
This maintenance schedule depends on fuel quality. It is applicable only when
using a qualified fuel <"EN590 or equivalent">. If the diesel fuel specifications
don't meet the EN590, it must be replaced more frequently. If there are
some important safety matters like fuel flow restriction, surging, loss of
power, hard starting problem etc., replace the fuel filter immediately regard‐
less of maintenance schedule and we recommend that you consult an au‐
thorized Kia dealer for details.
Manual transaxle fluid should be changed anytime it has been submerged in
water.
Inspect for excessive valve noise and/or engine vibration and adjust if neces‐
sary.
We recommend that the system be checked by an authorized Kia dealer.
For your convenience, it can be replaced prior to it's interval when you do
maintenance of other items.
REMARK
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