Polaris PREDATOR 90 Owner's Manual page 154

Drive Chain Inspection and Adjustment
Regularly lubricate the drive chain with Polaris chain spray lube or an approved chain lube.
See page 168 for the part numbers of Polaris products.
CAUTION
Washing the drive chain with a high pressure washer or gasoline can cause
premature wear and drive chain failure. Don't use a high pressure washer or gasoline
to clean the drive chain.
CAUTION
Adjusting or operating the ATV with improper rear drive chain slack can result in
severe damage to the transmission and drive components. Always make sure the
slack is within the stated specifications.
Maintenance
151