Coolant

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The Radiator Coolant keeps the engine from overheating while protecting it from rust and corrosion. It also prevents it from freezing, so is sometimes called anti-freeze (antifreeze).

Straight water can be used in a pinch, but is subject to rust and to freezing, and water which has not been demineralised can cause particle build up in the cooling system.

Daily Care

• CAUTION: Do not check at gas-station, but only when radiator is cool to the touch
• Remove cap and if fluid level is more than 1 inch below opening, add Coolant. Do not fill to the top.

Overview

Fill the radiator with demineralised water in a 50/50 mix of coolant/antifreeze. If you live in freezing areas, check the coolant container for instructions (which may require a 30/70 mix in very cold areas).

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Specifications

• Coolant capacity: 4.9 liter (5-3/16 US quart, 4-5/16 imperial qt)

Many of these brands listed below have changed names.

Antifreeze/Coolant for radiator

Recommended:

• Producing: Antifreeze coolant L.L.C. (Nissan "Long Life Coolant")
• Shell Shellzone

Acceptable:

• Chevron Atlas Perma Guard antifreeze
• ESSO Long Life Coolant
• ESSO Atlas Long Life Coolant RAD
• Mobile Permazone
• Sunoco Permanent Type
• Texaco Antifreeze Coolant
• Texaco Startex Antifreeze Coolant

Any modern antifreeze/coolant that is compatible with aluminium parts should be acceptable. The Datsun 1200 uses an aluminium head and water pump.

Failure to use coolant with anti-corrosive properties or failing to replace coolant regularly will result in rapid degradation of the aluminium parts.

Check coolant condition using a tester for this purpose, or drain and replace it every 2 years with new, properly mixed coolant, regardless of the manufacturer's claims of years/mileage.

50/50 coolant concentrate and DEMINERALISED water.

Failure to use demineralised water can result in scale build-up in the system. This creates an insulating barrier which reduces the transfer of heat from engine parts to coolant, and coolant to radiator. If the buildup is severe enough, the tubes in the radiator and heater cores will be completely blocked and coolant will not flow.

Using a 'lean' mixture of concentrate-water will not protect from corrosion.

Using too 'rich' of a mixture is expensive and can cause degradation of hoses and other parts, ineffective heat transfer, and ineffective mixture of protective ingredients throughout the system.

Replacement

The Maintenance Schedule calls for replacement of the engine coolant every two years. Use long-life coolant.

When draining, remove the engine block drain plug too.

When removing this plug, be sure to use a tight fitting 6-point socket/spanner. Failure to do so will result in stripping the corners off the head of the plug. These were manufactured from a very soft steel and are very easy to round off if the incorrect tools are used. You were warned...

Once removed, most of the time you will find it won't drain because decades of rust and scale and crud builds up in this low flow area of the coolant system. Use an old drill bit to hand-drill your way through the crud until it starts to drain, and then stick a running garden hose in the radiator with the radiator hoses connected. Use some thick/stiff fencing wire to poke and scrape around deep into the engine block and break up the remaining chunks inside so the water from the garden hose flowing through will wash it all out. Leave it running until the water comes out clear and clean.

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Cold Weather

Anti-freeze coolant protects the engine cooling system from freezing.

Be sure to check that the coolant has these properties as some don't (most do though).

Failure to do so can result in heater and radiator core damage (the frozen fluid expands and splits them apart) among other things.

Use the correct mixture of concentrate-water. Glycol on it's own actually has a freezing point similar to water on it's own. Adding water actually lowers the freezing point (up to a point, then it raises back up when the mixture becomes too lean)

To enable faster starts and lessen wear in sub-freezing temperatures, consider installing a Block Heater.

Part Numbers

USA

SBNLL-C0001 COOLANT-NISSAN LONG LIFE 2 LITTER(0.4
SBNLL-C0002 COOLANT-NISSAN LONG LIFE 4 LITTER(0.8
SBNLL-C0003 COOLANT-NISSAN LONG LIFE 18LITTER(3.9
10125-62200 N.C.S. SEALER (1 CARTON-96

Other Mixtures

If the vehicle is using lots of coolant (eg, cracked head/block, bad head gasket etc) and you're too lazy/cheap to fix it and too cheap to keep buying proper coolant, but don't want to damage your engine parts via corrosion, you can use a soluble oil-water mix.

This is commonly used in machine shops to cool cutting tools (saws, lathes, drills, milling machines etc)

You can usually buy gallon bottles for around the same price as same sized proper engine coolant concentrate, but the mixture is usually a lot leaner (around 250mL of oil to 4L of water) so you can make a LOT of mixture using the one bottle.

If you've ever wondered what that oily stuff is in a bottle of Bars Leaks that turns white when mixed in water, that's what it is.

The mixture can be topped off with plain water a fair bit before the mixture becomes too lean - top it up with a little more of the oil every now and then to get it nice and milky again.

Seems to do the job regarding corrosion protection, but heat transfer, anti-freeze, and condition of rubber parts and whatnot cannot be guaranteed...

The mixture does tend to separate after long periods of sitting so it's not recommended for vehicles being stored for long periods.