Coolant change question (Testarossa).

Not a Testarossa, but before summer I just remove 5l of coolant and replace with distilled water + water wetter. I just do the opposite for winter (add 5l of fresh -37°C coolant) for winter storage. So I basically replace a third of my coolant additives every 6 months.

For drainage, I only use the radiator petcock not the plug on the block. When I need to thoroughly clean the system I remove the temperature fan switch and flush 5 times with 5l of distilled water.

As for coolant I prefer to use coolant with silicate: although it is less efficient it does protect aluminium better. This being said the best coolant additives are dependant on the type of water used (US, asia and Europe are different), so your supplier may provide you with other types of coolant, but the issue is to favour a coolant designed for aluminium that reduces cavitation.

 

Remove the plugs on the engine, it is not hard.

 

Just draining from the radiators will be sufficient. Draining the block is not that big of a deal if you don't do it. I would only drain the block as well if it's coolant that is contaminated or faulty.

 

Coolant additive packages wear out. Draining radiators and not the block is a waste of time. Its like brushing your upper teeth because the lowers do not matter.

 

When you drain the engine from the plugs on the backs of the heads, the coolant will flow down into the precats under the heads and soak the insulation in the precats. It make a toxic stinky coolant steam when you fire the car back up for the first time for some moments. I use flexible funnels under the drains in the heads to keep the coolant out of the precats when draining out the coolant.