I recently purchased a 2005 V6 Mustang. I think I read somewhere that flushing certain old fluids would damage the engine, as opposed to refilling them. Is there a way to prevent engine damage doing a full flush for all the car’s liquids, or should I take my time refilling them as needed while I use the car as my daily?
The only way to damage the engine if you overheat it. So keep an eye on the temp guage and SHUT off engine if the temp gauge gets much past 12 'oclock. The danger is a potential air bubble in the newly filled cooling system. If you take your time, wait till the fresh coolant 'settles', it is a non-issue. That v6 has been known to crack the thermostat housing (plastic), check for leaks regularly there. Temp guage should never go past half way on those. Slightes change in normal reading cooling system level should be checked. Oil change is a non issue.
Avoid flushing auto transmission services that use a solvent. Just replace old fluid. NEVER use a solvent based engine flush in the crankcase. MMO, Seaform, shit like that. The only way to tell if you have a neglected engine with sludge, rare in modern cars but still possible, is to pull valve covers. Even then you are better off doing short oil change intervals with group IV oils. Coolant system flush products are OK. Just refill properly like Juice said and never use tap water or well water high in minerals. They will leave deposits. Distilled water only. Top off battery with distilled water also. Tap water tends to have a high PH and will neutralize battery acid somewhat.
Welcome to the forum and to tinkering on cars! If I might make a suggestion: purchase a Haynes manual for the car. Haynes manuals are not the best, but they're really good for beginners. I recommend reading all of the sections of the book that explain the basic functionality of the car's systems so you have an idea of how things work. There are also instructions in there for doing fluid flushes and such.
Free, online shop manual for your car at http://iihs.net/fsm/?d=1. I use it all the time; it's very easy to use.
To really do it right, the distilled water going into the eng cooling system should be vac filled. Use 100% synthetic for the eng oil. Use 100% synthetic for the auto tranny, if it's an auto.
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