Coolant Recommedation

[Marc Haibeck]

The question often comes up about what is the best coolant for the LT5 engine. I recommend the OE style conventional green coolant. I have found that Dex-Cool causes swelling of the OE LT5 head gasket.

Since it is possible that organic corrosion inhibiter softens the head gasket material, coolant containing organic corrosion protection should not be used in the LT5 engine. The possible values of using organic corrosion protection are small. Dex-Cool claims extended service interval and possible longer water pump seal life. It is not worth taking even a small risk for those benefits since the consequences of head gasket damage are huge.

Use coolant that has the following characteristics:
- Labeled, “For older vehicles.”
- Coolant that is colored green
- Texaco UPC number 76568 12016
- Chevron UPC number 23968 10000
- GM specification 1825M coolant. The current pn is 12378560.
- AutoZone part number 540722. The UPC number is 52948 59081.
- Blue Mountain UPC number 74804 01858

The green coolant might not be available in a brand that you like. However the correct formulation is more important than the brand. Avoid “Universal” coolant. There is no need to compromise when the green coolant is available. Retailers like universal products because they reduce inventory costs, universal coolant is not the best for your LT5, the conventional green coolant is.

For detailed information about my observations of LT5 head gasket swelling see:
http://www.zr1specialist.com/HAT%20W...d%20gasket.htm

[Dynomite]

Originally Posted by Marc Haibeck

The question often comes up about what is the best coolant for the LT5 engine. I recommend the OE style conventional green coolant. I have found that Dex-Cool causes swelling of the OE LT5 head gasket.

Since it is possible that organic corrosion inhibiter softens the head gasket material, coolant containing organic corrosion protection should not be used in the LT5 engine. The possible values of using organic corrosion protection are small. Dex-Cool claims extended service interval and possible longer water pump seal life. It is not worth taking even a small risk for those benefits since the consequences of head gasket damage are huge.

Use coolant that has the following characteristics:
- Labeled, “For older vehicles.”
- Coolant that is colored green
- Texaco UPC number 76568 12016
- Chevron UPC number 23968 10000
- GM specification 1825M coolant. The current pn is 12378560.
- AutoZone part number 540722. The UPC number is 52948 59081.
- Blue Mountain UPC number 74804 01858

The green coolant might not be available in a brand that you like. However the correct formulation is more important than the brand. Avoid “Universal” coolant. There is no need to compromise when the green coolant is available. Retailers like universal products because they reduce inventory costs, universal coolant is not the best for your LT5, the conventional green coolant is.

For detailed information about my observations of LT5 head gasket swelling see:
http://www.zr1specialist.com/HAT%20W...d%20gasket.htm

The detailed information attached describes The three causes of LT5 Overheating and resulting Cylinder Head Gasket Failures which in itself is as important as using the wrong coolant making the overheating issues even more serious


Thanks Marc

[ZZZZZR1]

Marc


Thanks for posting this!!! This question comes up and most of us can't remember what exactly is safe to use



David

[WVZR-1]

Marc - it's certainly a "timely reminder" and appreciated

[Hib Halverson]

What would a "coolant thread" be without my lunatic-fringe alternative.

For most of the 20 years I've owned "Barney" my purple '95, I've never run any antifreeze at all in the cooling system. Just straight water and one bottle of one of the two leading coolant additives, Gibbs Driven "CSP" or Red Line "Water Wetter".

Why straight water?

Water is a better coolant because it absorbs more BTUs per gallon than does a 50/50 mix of water and antifreeze. Of course, when you don't use antifreeze you MUST have some other form of the anti-foaming and anti corrosive chemicals that come in antifreeze. Radiator Relief or Water Wetter supply that chemistry. In fact, Water Wetter uses a calcium-based corrosion inhibiter similar to that in Dexcool. Additionally, both products contain a "weting agent" which further improves water's ability to cool by enhancing the transfer of heat from the cylinder head and block to the cooling jackets.

Now...the cautionary statements:

1) For obvious reasons, you can't use straight water if your car is subjected to below freezing temperatures when it's parked overnight or stored.

2) You must change that coolant mix every 24-months regardless of mileage.

[WydGlydJim]

I was surprised to find Dex-Cool in the Lingenfelter...the fluids had just been changed when I bought it, so I didn't worry about it for quite some time, then when I found Dex-Cool, I just supposed to change it at the next available time.....well that was when I changed the starter a while back.....I flushed it three times with straight water and the water ran very clear. I decided to do the fill with Pentosin Pentofrost NF. What sold me was "Mercedes Benz all years" "Porsche 924,928,944,968 all years" "BMW all years"
http://www.pentosin.net/f_antifreeze.asp
Thoughts?

[Marc Haibeck]

Here's an update about green formula coolant availability. I believe that it is still important to stay with the OE type color coded green coolant. Green coolant can be hard to find. Some auto supplies will try to sell "universal" or some other coolant because that is all they have. It might take some searching but green coolant is still available.

As of this date AutoZone has it in their house brand. Part number A003.

NAPA has it in their house brand. Part number NAF1GAL. The NAPA near me also has the Zerex brand. Part number ZRX ZX001.

A local independent auto supply stocks it because they want to support the classic car market. It's labeled FVP Original Green Formula. Part number FVPGreen-Gal. It's distributed by FVPparts.com.

[efnfast]

Thanks Marc, doing coolant this weekend. Really nice to have confirmation of what to use from a trusted source.

[We Gone]

Great Info.

[Schrade]

Good info there Mr. H...

I would NEVER recommend GM Red coolant.

In 4 vehicles I've owned with the Dex-sludge, ALL 4 had the 'plug', including an '02 1-ton, bought new, which was my personal vehicle of my delivery fleet business. All were immaculately maintained by me, and the 1-ton stayed running. After 100k, about 14 months, it had the 'plug'.

I think GM lost a class action over this issue...