jbres wrote:
Have a question regarding changing coolant on my truck.
(truck is a 2007 gmc sierra 2500HD classic 2wd w. 6.0 gas job)
I had a gift card to Tire Discounters so took my truck there today to get a coolant flush/change. I told them I wanted it changed with something "dex-cool" approved as it states in my owners manual. Guy behind the counter says we use "Valvoline Max Life" which is a universal green antifreeze that mixes with any color and can use on any car or light truck.
Antifreeze I had in my truck was red and still in there from factory with 68,000 miles.
My question is was I wrong with letting them use the "Valvoline Max Life" as a substitute? It technically I guess isn't "dex cool approved" but also is universal, so is confusing me. I am trying to debate whether or not I need to get out the coolant they put in, and make sure to get back in the dex cool. Guy behind the counter actually said he would never use dex cool in any of his vehicles.
Any opinions or suggestions, I am trying to do some preventative maintenance and avoid head gasket failure years from now.
Thanks!
Personally, I think you know have a mess and IMO your biggest mistake was taking it to a place like Tire Discounters to have this type of work performed. All this thinking your might safe a couple of bucks since you had a discount card/coupon. These "quickie" places IMO only do it "their way" and which almost always is not the "best" or even "proper" way.
I'm not going to try like some others to claim 100 years of changing 1,000,000 vehicles of coolant or some other unverifiable claims, but over the last 12+ years have read hundreds if not thousands of coolant discussions mainly over on the DieselStop web site and will make the following comments for your consideration based on what I have learned or "gleaned" from those .... they are:
1. Personally I would not use DexCool in a vehicle not because it's an especially bad coolant, but it has it's "quirks" and is more susceptable to things effectiving it like the air and contamination issues already mentioned. However, it obviously works or GM would not be using it for many years, but they are the only major manufacturer using this type of coolant.
2. The two single biggest mistakes made in coolant maintenance is not doing a proper flush with "DISTILLED" water and if you are chaning types of coolant not again doing a proper flush to start with to get every trace of the prior coolant out.
3. The coolants of today are not those found just 5 years ago and most extended coolants now days are "low silicate" or "silicate free" and the previous issue of silicate drop out is now close to non existant.
4. I would never add things that I would call special additives such as rust inhibitors except for those recommended by either the car manufacturer or the coolant manufacturer. These "approved" additives are thing such as the "booster" for extended life coolants like the CAT and nitrite boosters for coolants such as the G-05 coolants used mainly in Ford/Chrysler/Mercedes vehicles.
5. Special "cleaning" type additives are IMO unnecessary and I would never have my vehicle serviced by a place that uses a machine like the B&M one that advocates their line of "cooling system cleaners". While almost all coolants say they can be mixed with others that might be true, but what they don't say is that you IMO loose all the benefits especially the longer life so while your engine won't blow up or die immediately you have wasted $$$ and have basically gained nothing and will in generally be back on around a 3yr or 36K change interval. This reduces life is also in play if you don't use distilled water only as the water part in your coolant mixture.
6. Now days there are basically 4 what I call types of coolant. One is those that are a mix of PG and EG "special" coolants that are water free like EVANS. Another is the typical straight EG what we often call the "green" coolant like prestone. The third are the OAT coolants which are mainly ones like the CAT, Mobil DELVAC, Shell Long Life, etc. which generally have the words "extended life coolant" (ELC) in them and DEXCOOL is a subcategory of these OAT type coolants. The final type is HOAT or Hybrid Organic Acid Technology coolant with the best know as Zerex G-05, Motorcraft "Gold", or the Mopar/Mercedes brand. There are also some minor classes used in some foreign cars like the Valvoline Asian Import and some others I don't even remember. Now days most big rig diesels use the OAT ELC type coolants. The HOATs are used by both Ford and Chrysler/MB in both their gas and diesel engines. To my knowledge only GM uses the special subclass of OATs know as DexCool and I'm not sure if it's used in both their gas or diesel engines or a subset of those.
7. Servicing your coolant doesn't require special procedures like back flushing or "power flushing", only some attention to detail and use of proper materials. Now below I will list my recommendations for two scenarios, one where you are changing the type of coolant such as I have listed above and in fact I would use that procedure if I was even changing brands within a type since the additional cost is zero and only time is involved. The second is simply replacing the coolant with the exact same type because you have met the stated service interval for that coolant. A word on this "service" interval. Almost all vehicle manufacturers have a longer "first service" interval with shorter subsequent intervals mainly because they do not account for a proper flush or ensuring that when you add you new coolant you are mixing that with "ONLY" pure distilled water. With both my procedures below IMO you can easily establish what I will call a new hybrid "service interval" between the factory fill number and the lower service interval listed in most vehicle maintenance schedules. For example for a factory fill state interval of 5Yr or 150K miles with a 3yr or 50K subsequent interval you can easily IMO go to around 4Yr and 100K miles. Now obviously if you go with these "extreme" or life long coolants such as the CAT ELC and a couple of others that require just adding boosters then I would just follow whatever they recommend for that specific coolant. Personally I'm a big fan of the HOAT Zerex G-05 coolant since it has a decent change interval and I just like to get new stuff in there every few years. Now on to the two scenarios I mentioned.
CHANGING FROM ONE TYPE OR BRAND TO ANOTHER TYPE OR BRAND OF COOLANTHere the most important thing is to get every trace or better than 99.5% of what is now in the vehicle out. This scenario has the same objective as the second one below and that is to get you to a place where when you add your new coolant you are only mixing it with 100% or that 99.5% number of "PURE DISTILLED WATER". However since you have a different type of coolant I recommend flushing your system first using normal TAP water. You can do this by the old drain the radiator and fill scenario with getting the engine up to temp with the heater running between the drain and fills. I would recommend doing this procedure about 4 to 6 times and if your are not doing this during freezing weather there is nothing wrong in leaving that mostly water in there for maybe a day or two so your normal commute gets things well mixed up and the engine up to temp. Now don't leave it in there for 500 miles, etc. so some common sense is needed. Now move on to the second scenario.
CHANGING THE SAME BRAND AND TYPE OF COOLANT OR ADDING NEW COOLANT TO A SYSTEM THAT HAS BEEN FLUSHED WITH NORMAL TAP WATER.
Here this is very similar to the first, but now you will only be using distilled water for your drain and fills. Based on past experiences and calculations to get close to 100% distilled water you will need about 1.25 times the stated cooling capacity of your vehicle including the heater in distilled water and you simply do the old fill and drain until all but enough distilled water is left that you get from a normal drain of the radiator. A normal drain should remove just over 1/2 of the coolant in an engine so after your multiple drain and fills at your last drain you should have just under 1/2 of the capacity of the coolant system is PURE DISTILLED WATER. You then add enough 100% strength coolant to get you to that 50-50 to 60-40 coolant to water ratio and then top off your system with the distilled water that your saved. You will have a little distilled water and probably some coolant leftover at this last step and then just mix those to get say a 60-40 mix to use for topping off if needed. Remember this open mix has a shelf life and I would not use it past your next coolant change, but discard any saved at that time that is more than about a year old.
I know this is a very long winded post, but there I feel are some important points here and if one does decide to have someone else do the work the concepts of "NO CLEANERS", "GETTING ALL THE OLD COOLANT OUT", and having only "100% DISTILLED WATER" in your cooling system when adding new coolant for a coolant change are a MUST IMO for that shop to accomplish and hopefully you have some insight on what you should be asking to ensure these basic goals are met.
Finally, if in doubt come back and ask or research carefully before taking action or you will find yourself re doing what was done at a greater expense and with wasted time/effort.
Larry
