Coolant For Closed Cooling System; Crankcase Oil - Mercury MerCruiser MCM 454 Mag MPI Service Manual

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Coolant for Closed Cooling System

Alcohol or Methanol base antifreeze or plain water, are not recommended for use

in fresh water section of cooling system at any time.

We recommend that the coolant section of closed cooling system be filled with Extended

Life Ethylene Glycol 5/100 Antifreeze/Coolant mixed 50/50 with purified water. In areas

where the possibility of freezing does not exist, it is permissible to use a solution of rust inhi-

bitor and water (mixed to manufacturer's recommendations).

If any non-compatible coolant is added to this coolant, coolant must be changed every 2

years or 400 hours, whichever occurs first. All coolants other than Extended Life 5/100

Ethylene Glycol Antifreeze/Coolant must be changed every 2 years or 400 hours, whichever

occurs first.

MerCruiser V-8 engines can use any type of permanent antifreeze or any brand antifreeze

solution that meets GM specification 1825M.

To help obtain optimum engine performance and to provide maximum protection, we

strongly recommend the use of Quicksilver 4-Cycle 25W-40 Marine Engine Oil. This oil is

a special blend of 25-weight and 40-weight oils for marine engines. If not available, a good

grade, straight weight, detergent automotive oil of correct viscosity, with an API

classification of SH, CF/CF-2, may be used.

In those areas where Quicksilver 4-Cycle 25W-40 Marine Engine Oil or a recommended

straight weight oil are not available, a multi-viscosity 20W-40 or, as a second but less prefer-

able choice, 20W-50, with API service ratings of SH, CF/CF-2 may be used.

IMPORTANT: The use of non-detergent oils, multi-viscosity oils (other than Quicksil-

ver 25W-40 or a good quality 20W-40 or 20W-50), synthetic oils, low quality oils or oils

that contain solid additives are specifically not recommended.

The chart below is a guide to crankcase oil selection. The oil filter should always be changed

when changing engine oil.

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Quicksilver 4-Cycle 25W-40 Marine Engine Oil

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SERVICE MANUAL NUMBER 23

90-861326--1 MARCH 1999

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