When you flush the cooling system can one use a product like a super flush bought at autozone etc.., or just use water and flush twice or more?

Thanks, Randy
1998 A4 2.8 (Just begining to upgrade/mod )

 

If you have origonal G-12 in there, flush with water.

 

Thanks, thats whats in there but I thing I have a heater core blockage since no heat from the heater. I'll flush it twice and put G12 in again. I recently had the timing belt done along with the water pump/thermostat etc. Only after the first cold spell here in Houston did I notice no hot air. Thanks again

 

You may just have an airlock in the coolant line to the heater core. Bleed the line.

If that doesn't help, borrow a vagcom and check the HVAC system for codes.

 

Did a quick bleed by letting air out of the resevoir, got some warm air now. So an air block is probably the problem. Thanks for everyones advise.