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Radiator Fluid Change

I have a GM vehicle. I had the Dex Cool fluid replaced at 70,000 miles. A local garage changed the fluid and probably used aftermarket product. Owners manual says that the fluid should be changed every 30,000 miles or 5 years. Both of those are up this year. Should I tackle this job? Will I need all new hoses? 2004 Chevy Silverado 1500 5.3 engine. Thanks for any advice!

What color is the coolant in there now? If it is green or yellow, then they did use an aftermarket coolant. If it is pink or orange, then they used dexcool or a dexcool compatible coolant.

If you do this yourself and you have dexcool or a dexcool compatible coolant in there, they you must use the same thing unless you completely drain the block, radiator and heater core and all hoses. You do not need to flush and I would recommend that you do NOT flush the cooling system. You have taken good enough care of it so it should be in pretty good shape.

The hoses are 12 years old so changing them, and the thermostat would not be a bad idea. Get a new radiator cap while you are at it. If you do a complete drain, then you can use just about any coolant you want to use. Most aftermarket coolants are a HOAT formula and will be labeled for use with “all colors, all types” or something like that and also labeled for 5 years or 150k miles (100k miles on some). These are safe coolants for use in your vehicle and will last the claimed time/miles and then some.

If you don’t completely drain the old coolant and you use a different type, then the life is shortened to about 3 years and 50k miles. I suspect that your previous mechanic may have done this and that is why he recommended a shorter interval.

Done right, your cooling system should give you 5 more years of reliable service, and 5 more if you do the coolant change again in 5 years.

First you need to know what coolant was put in. I dumped dex for peak lifetime global whatever. 5 years on it now, have to read up on it to really know when I should do anything. Hoses to me are subject to replacement as needed, but a qualified mechanic should be able to asess your hose conditions and recommend replacement or not to worry. 03 trailblazer 170 k miles

"A local garage changed the fluid and probably used aftermarket product."

There are all sorts of crazy horror stories about Dex Cool. Ignore them. I have lots of GM cars that have been running on it for years. It works great, as specified.

Was the aftermarket product equivalent to the Dex Cool brand?
Do you have a radiator cap?

If you can answer “yes,” to both questions, here’s what I’d do…
Don’t turn this into a big chore or nightmare.
I do it standing up. I actually run a clear plastic tube (1/4" ?) (or Wal-Mart available siphon tube) down through the cap opening and try and get it to “bottom out” in the radiator. I start a siphon and drain it into a gallon jug (or 2 gallon jug). You might have to stop the siphon, change jugs and restart if the gallon is used.

There is no mess and I measure what came out and replace it with the same amount of new, properly mixed (or pre-mix) antifreeze/anti-boil Dex Cool solution. It will leave some fluid in the system, but will change the majority of it. If it won’t all fit in then pour it into the plastic reservoir and the engine will call for it after it goes through normal hot/cold cycles.

I have had problems removing covers or problems with stuck drain plugs before I adopted this method. Who needs the hassle?

Oh… google the proper the proper fill procedures for your engine. There might be a “purge valve” (needle valve that you open and then close) to allow air to escape while filling or some other recommended procedure.

It’s not Rocket Science.

Thanks for the advice. The garage used a dexcool compatible coolant. I am planning on doing this myself after reading and researching online. I will do a visual inspection of the coolant hoses and replace as needed. Didn’t realize how easy of a job this was!

I just had my Dex changed and continued with Dex and had all the hoses and thermostat done at the same time. The problem with Dex is that you have to be super careful with any air being introduced or remaining in the engine. So after going through the same decision process of me doing part and the shop the rest, I just decided it wasn’t worth it to fool with. I don’t know about Dex compatible. I think its either Dex or not.

“There are all sorts of crazy horror stories about Dex Cool. Ignore them.”

Really? It must be nice to drive brand new vehicles. I can’t tell you the number of cars and trucks that I have seen with the slimy greenish black swamp water residing in the cooling systems of DexCool equipped vehicles. Crazy horror stories…I think not.