Dex-Cool

[THEFERMANATOR]

This discussion is all well and good Will, and I appreciate it alot, but I need to change my factory fill before I take a 1000 mile run to Colorado in a month and since I'm embarrassed to say (sort of) I have 220k+ trouble free miles on the OEM, shouldn't I be reasonably confident that today's Dex is a whole different deal than the early lawsuit days?

Yes, it is several times over. By 06 you were on the 3rd formula for DEX-COOL that I know of. The early formula had problems eating gaskets and was quickly changed out(yet I have worked on cars with the origanal 10+ year old dex-cool in them, and it looked good enough to pour back in. The hoses even still felt good.) I think it was around 99-00 that they made teh first change to it to help with plastics and o-rings. ALot of people also don't realize that when DEX-COOL came out there hadn't really been much long term testing done because it was so new, and it wasn't known then that the first formula would attack standard cooling system o-rings. It's safe to say that the dex-cool we get now is nothing like the origanal that had all the lawsuits. But yet just like so many still claim that all GM diesels are converted gas engines, many just can't turn loose of the past. I just worked on an 04 with the origanal dex-cool in it, and I put it back in because it looked so good still, and there was ZERO corrosion of any kind inside the engine.

 

[Will L.]

Don't get me wrong I hope everyone running has the best luck. I became good friends with a certain chemical engineer and his comment is the corp is forced into multiple redesigns and has filled for the ability to go back to ethelyne glycol to no avail as recent as the bail outs. Not all our test engines had problems. Your mileage may very. We had 1 - 6.5 engine that was a 165,000 mile / annual truck that threw the front balancer and never broke the crank. Not the norm but it is there.
Ferm- much respect and you are probably a far better wrench than I. That old of dex how high was the nitrate readings? just wondering.

 

[btfarm]

And likewise Will, don't take us wrong. Expertise such as you bring to the table is welcomed with open arms around this particular forum. I actually already knew which way I was going but wanted to feel fairly certain I was going to get the latest version of dex by brand. I've been wrenching on everything I own since the early '60s and work as a mechanical design engineer so, by personal and professional nature, I DO welcome these discussions.

 

[THEFERMANATOR]

Don't get me wrong I hope everyone running has the best luck. I became good friends with a certain chemical engineer and his comment is the corp is forced into multiple redesigns and has filled for the ability to go back to ethelyne glycol to no avail as recent as the bail outs. Not all our test engines had problems. Your mileage may very. We had 1 - 6.5 engine that was a 165,000 mile / annual truck that threw the front balancer and never broke the crank. Not the norm but it is there.
Ferm- much respect and you are probably a far better wrench than I. That old of dex how high was the nitrate readings? just wondering.

I don't have any test strips, so I just eyeballed and taste tested it(not literally). I've seen some of teh dex-cool issues, but I feel it is way blown out of proportion. PRESTONE has been the only anti-freeze I have had real trouble with(had 2 trucks in less than 2 years with blown head gaskets with the stuff from pitting and ate up head gaskets) and will avoid at all costs, but so far I have yet to have a problem with ZEREX. I'm not trying to give you a hard time or anything, but I have seen peopel dog teh stuff, and turn around and swear by CAT ELF which is almost the same exact stuff as DEX-COOL. I believe the new DETROIT DIESEL stuff is also a DEX_COOL variant as it appears to be fro mthe looks of it nothing more than the asian vehicle dex-cool. Just seems that certain applications had problems with it more so than others. And some problems that were blamed on DEX-COOL(like VORTEC intake gaskets on the 4.3L, 5.0L, and 5.7L) had nothing to do with it as I seen just as many problems with the green stuff in them.

 

[GM Guy]

All the gassers currently on the farm that came with dex, still have it, so only two. the 98 GMC with over 200K, and leaky gaskets, but nothing looked damaged or corroded, so we will be dropping as much as possible when we change head gaskets, then filling back up with dex.

the other rig running it is the sister's 00 Bonneville that is closing in fast on 250K miles. coolant still looks good, and no consumption. IDK the history on it, or the intake gaskets.

the only other rigs that had it OEM and dont anymore are all the 6.5L's 96 and up, and a now sold 00 3500 chassis cab with the 350. I did drain a shitty mixture out of the project 96 K2500HD, likely contaminated via an universal coolant, but it started off as Dex.

some, if not all coolant problems here are likely caused by dad convincing himself that farm well tap water full of minerals is ok to use in cooling systems, whereas I buy gallon jugs of distilled water from Dillons (a Kroger store chain in case you dont have one) or Wal-Mart. just like "any synthetic 75w90 is ok to use in a NV4500", dad ends up costing himself much more by his cheapness than he saves.

I might end up putting the 96 K2500HD back to dex when I get it back together, as it looked good as well.

due to fear of cross contamination, anything allready green will likely stay green, and I found an affordable Green coolant locally that specifically says heavy duty diesel applications, pre charged with SCAs and all, and it costs like 11 bucks a gallon for concentrate. I too like the Zerex over others in Green coolant, seems to meet far more specs than others, its all i use in the 91 Chevy.

Ferm, I heard the vortec 350 intake gasket issues were caused by the intake manifold bolts not being perpendicular to the mounting surface, but rather go straight down, so about 45 degrees to the mounting surface, causing it to work over time. Is this correct?

 

[btfarm]

I saw Dex at Rural King in Shell Brand with the GM approval and SAE 3306 (IIRC) ratings at $11/gal for undiluted. That's a good price.

 

[THEFERMANATOR]

Ferm, I heard the vortec 350 intake gasket issues were caused by the intake manifold bolts not being perpendicular to the mounting surface, but rather go straight down, so about 45 degrees to the mounting surface, causing it to work over time. Is this correct?

Contrary to what some say, yes it was a design issue. The bolts going downward creates more clamping force on teh intake, but on the other hand it crushes the gaskets. A few years back they revised them and added a metal sleeve in the gasket to prevent the plastic from getting crushed oer time. Alot of repeat failures were also due to people changing them and not torquing them properly. They only get torqued to 110 inch pounds IIRC, which isn't much. I've seen peopel break out a 12" 3/8" drive ratchet and crank em down, and then wonder why they leak again in 3 months.

Alot of peopel said DEX-COOL took them out like on the V-6's, but this is 100% FALSE in EVERY way.

 

[WarWagon]

"Alot of peopel said DEX-COOL took them out like on the V-6's, but this is 100% FALSE in EVERY way."

Are you kidding me? The gasket material was proven not to be compatible with DEX! GM got to pay some money out and specifically reimburse me for the job on a 1999 3.1 V6.

I had to use a rare old low torque wrench from dad that went down that low to do the job on a 3.1 V-6. (New ones are made but I bet most don't have a inch pound one in your tool box.) I had to buy the fuel line tool and the special star sockets. Not only did the DEX-acid eat the gaskets it ate the aluminum on the intake and heads leaving severe pitting. I got lucky with just gaskets and new coolant as it held till better than 170K when it was totaled 10 years later. This was a car with 50K on it and less than 3 years old. Massive coolant loss and a puddle would appear on the front driver side manifold bolt.

GM can be ignorant with using the proper fluids for the parts in an assembly in the blind rush for minimum maintenance. I got to Lemon law a Trailblazer SS because GM used a 100K mile synthetic lube in the diff that had Eaton posi track in it. Eaton says to use regular dyno oil NOT synthetic. They say this because as GM found out the synthetic would burn the clutches up. After several diff rebuilds it was a Lemon Law winner. The internet had already solved the problem with a semi synthetic lube to stop chatter in corners and let the clutches live. GM changed the fluid spec 3 times till they got it right.

The Allison transmission fluid spec has changed coming from Allison as the Dex 6 is too thin. And also let the Trailblazer SS trans burn up on me.

So next time you guys say GM knows best I say :rof:. GM can't change things easy because they have lawsuits, a production line to stop, and have to spend cash. It costs GM money in lost lawsuits to admit a problem by a design or fluid spec change. It also costs money to engineer the change and test and certify with the EPA etc. So this is why people pushing the limits or solving a problem can successfully go against a GM spec. GM only changes when the warranty cost is excessive or other costs force them to.

GM is famous for cooling system designs that are close to non-functional.

This said after the first coolant change interval the cooling system is not going to stay closed. So long life coolant is a waste. The old hoses, water pump, radiator, heater core are all waiting to fail and open the system. There is no reason to run anything but the green stuff in really old equipment. The newer stuff with the gaskets and redesigned DEX worked out maybe. DEX has proven to have issues where the green stuff's limits are known well. If the water pump seal is all there is to worry about and you are changing that...

 

[THEFERMANATOR]

"Alot of peopel said DEX-COOL took them out like on the V-6's, but this is 100% FALSE in EVERY way."

Are you kidding me? The gasket material was proven not to be compatible with DEX! GM got to pay some money out and specifically reimburse me for the job on a 1999 3.1 V6.

I had to use a rare old low torque wrench from dad that went down that low to do the job on a 3.1 V-6. (New ones are made but I bet most don't have a inch pound one in your tool box.) I had to buy the fuel line tool and the special star sockets. Not only did the DEX-acid eat the gaskets it ate the aluminum on the intake and heads leaving severe pitting. I got lucky with just gaskets and new coolant as it held till better than 170K when it was totaled 10 years later. This was a car with 50K on it and less than 3 years old. Massive coolant loss and a puddle would appear on the front driver side manifold bolt.

GM can be ignorant with using the proper fluids for the parts in an assembly in the blind rush for minimum maintenance. I got to Lemon law a Trailblazer SS because GM used a 100K mile synthetic lube in the diff that had Eaton posi track in it. Eaton says to use regular dyno oil NOT synthetic. They say this because as GM found out the synthetic would burn the clutches up. After several diff rebuilds it was a Lemon Law winner. The internet had already solved the problem with a semi synthetic lube to stop chatter in corners and let the clutches live. GM changed the fluid spec 3 times till they got it right.

The Allison transmission fluid spec has changed coming from Allison as the Dex 6 is too thin. And also let the Trailblazer SS trans burn up on me.

So next time you guys say GM knows best I say :rof:. GM can't change things easy because they have lawsuits, a production line to stop, and have to spend cash. It costs GM money in lost lawsuits to admit a problem by a design or fluid spec change. It also costs money to engineer the change and test and certify with the EPA etc. So this is why people pushing the limits or solving a problem can successfully go against a GM spec. GM only changes when the warranty cost is excessive or other costs force them to.

GM is famous for cooling system designs that are close to non-functional.

This said after the first coolant change interval the cooling system is not going to stay closed. So long life coolant is a waste. The old hoses, water pump, radiator, heater core are all waiting to fail and open the system. There is no reason to run anything but the green stuff in really old equipment. The newer stuff with the gaskets and redesigned DEX worked out maybe. DEX has proven to have issues where the green stuff's limits are known well. If the water pump seal is all there is to worry about and you are changing that...

Read what I put in that post. I never said DEX-COOL didn't take out the V-6 gaskets, but it had ZERO effect on the early vortec gaskets(despite many wanting to blame it for them failing, I seen just as many fail with green in them after people changed out swearing the dex-cool ate them). Early DEX-COOL had compatibility issues with o-rings and some gasket material, that isn't in despute, but the dex-cool did not hurt the VORTEC intake gaskets. And DEX VI being thin has absolutely ZERO to do with why ALLISON does not reccomend it for use. It has to do with the additive package not being compatible with early seals, and that DEX VI gels at temps below -40. DEX VI is not that much thinner than DEX 3(roughly 1-3 points on the viscosity scale), but the thinner fluid is an attempt by GM to eek out every last bit of fuel economy they can.

As for going to green down the road, this is what leads to many problems with systems that had dex-cool in them. Green coolant is NOT compatible with DEX-COOL, and once the o-rings and such have had dex-cool on them, going to green normally dries them out and results in leaks and people cursing dex-cool when in fact it was there own fault for swapping it out. GM has made errors, but so has FORD, CHRYSLER, and any of the imports. Unfortunately alot of times wether we want to admit it or not, the consumer has to be the beta tester as some things just cannot be found out until long term use has taken place.

 

[WarWagon]

Vortec? :rolleyes5: You got me with that one.

 

[btfarm]

Vortec started with model year 1997 IIRC

 

[saratoga]

The only Vortec engine I had cooling issues with was the 97 7400 where the heater nipple rotted and broke off. That's between a 97 4.3L S-10, a 97 7.4L dually and a 2001 2500HD 6.0L.

Not related to the coolant because what did you expect to happen when you use a steel fitting screwed into an aluminum intake manifold? The replacement was aluminum IIRC.

 

[THEFERMANATOR]

Vortec started with model year 1997 IIRC

Pretty sure it started in 93 or 94 with the 4.3L, and the V-8's went to VORTEC heads in 96 when they switched from TBI to multi port injection. I've never seen one, but there was supposed to be some 454 VORTEC's in 95 in motorhomes.

 

[btfarm]

This should help:
Vortec

 

[WarWagon]

For 1500 pickups: 1993 4.3 V6 was TBI and underpowered at that. (160 HP?) 1994 was the 200 HP Vortec V6. I recall the Vortec system also has a vane in the intake manifold to change runner length with RPM etc. Maybe on Blazers?

1995 350's were not Vortec in Yukons anyway.

 

[btfarm]

Coolant Change Day

Yesterday was Transynd day and today was DexCool day.
Here's the shell stuff I used:



I drained it by pulling back the RH fender liner and pulling the lower hose. Much easier than I expected.



The fluid that came out was still looking pretty good for well over 200k-



I drained about 4 gal out, refilled with distilled water, ran until over 180* and circulating, repeated that proceedure then did my refill with new Dex and distilled. Heavy on the Dex concentrate since the remainder was diluted from the flush. Went for a 10 mile drive and topped off with another 3 qts or so.


To finish the day I put some new Westin SS steps on since the powdercoated black steel ones keep rusting out.

 

[saratoga]

:thumbsup:

 

[RI Chevy Silveradoman]

Nice Mike. I still cannot believe that GM did not put a petcock valve on these. When you drained, did you take off the fill reservoir cap?

 

[tanman_2006]

Looking good! I did the drain/fill x2 w/ Amsoil transsynd compatible and 75/140 amsoil in the rear today w/ new axles seals. After 50k on that fluid it was getting pretty dark but my tranny has seen 280* quite a few times. I bet the rear got pretty hot too. Didn't have oil for the tcase but it's on the way.

I need to find my coolant leak one of these days. Problem is it doesn't drip to the ground. Thinking oil cooler line and running down the valley or onto a manifold. I can smell it under hood so I'm LESS concerned.

Sent from: Source Unknown

 

[btfarm]

Nice Mike. I still cannot believe that GM did not put a petcock valve on these. When you drained, did you take off the fill reservoir cap?

I pulled the cap the first 2 times and forgot the 3rd. When I noticed, it provided a gusher...:agreed: Yeah, no drain petcock but it was actually harder to pull back the liner than take the hose off. Something positive about no worm clamp I suppose.
I took out the air box while I was at it for more room to work. 2 minute job anyhow.