Coolant

 
I tried searching many times but no matches. Since I bought my 2002 audi a4 i had to add coolant twice. Each time I just used the regular red coolant that you would use for any other engine (american, japanese). I found out that you have to use g12 a8d coolant which is red too. Is this gonna be a problem for my cooling system?
 
My coolant light is on again which means I have to add more coolant. What should I do now?
 
I have 75,000 miles.
 
Thanks

Flush the system. You can refill with G-12 and water, or
universal global yellow ant-freeze and water.

If it's leaking out, just use some distilled water, till you get the leak fixed. More often then not, it's the overflow tank leaking or the secondary water pump.

you could also check your coolant temp sensor.

I would try and find the leak first then refill with g12. The normal red stuff has a high acid count. Coolant has a voltage which the sensors need to read. So it is best to keep the proper coolant in your system

"Coolant has a voltage"
Relative to what?

I would check for leaks your car shouldnt use that much coolant. If its an A4 1.8 then you dont have ane afterrun pump. If I had to guess I would say one of the following coolant flange on the backside of the head, oil cooler coolant lines, pressure tank or the water pump. I would also check the bleed screw on the coolant pipe if you are one of the unlucky ones with the plastic screw. Most of the leaks are easy to spot with just a light but to check the back of the head you will need a mirror. As for the coolant question I would flush the system and get g12 back in it after you fix the leak of course. Hope this helps.
 As for the voltage comment yes coolant carries a small voltage but the car does not check this voltage. If coolant is used for an extended period of time the voltage will increase causing a condition called electrolisis (sp).