SCORE! i think?

[WagonMan]

A friend of mine works at a place that makes medical equipment. The company throws out anything that has a use by date. I have gotten Thread locker, glue, cleaners etc. that are all still good. Yesterday he gave me a 5 ounce tube of silicone heat sink compound, never opened. I believe this is what is used in the distributors on the ignition module.
Opinions on whether to use it or not? Shelf life is 5 years and it just expired. WagonMan

[jaywish]

I would but hey many folks would not do what i have done.

[gadget73]

Its basically zinc oxide (sunscreen) in a silicone grease. Not much to go bad honestly so long as the tube is closed. It will eventually dry out if you leave the cap off.

[kishy]

I run AS5 under my ignition modules, mainly because I always have it available anyway. Sometimes I use generic white CPU thermal compound that I can't bring myself to put on actual CPUs newer than a Pentium III.

[94Magna_Tom]

Companies do a lot of research into their products. The expiration date must have some significance. That being said, they must build in a significant safety margin regarding the listed expiration date, so my guess is it's probably good for 50% longer than the expiration date. Obviously it's not good one day, and bad the next, but it will probably suffer some loss of its quality over time. I would use it...for a while.

[EaOutlaw1969]

In my opinion heat sink compound should not be used if expired or if it is close to the expiration date. especially on a part that can leave you stranded.

Lets face it saving a few bucks could cost you more in the long run with shorter run times on parts and possible towing charges.

If it was the end of the world and that was the last tube of heat sink compound in a 100 mile radius sure I would use it yet why add the stress to your life over saving a few bucks.

None of this even takes in consideration if the Dow Product is suitable for the parts and or environment it will be operating in.

This shows Dow SC 102 Being suitable for Automotive applications and other uses

https://samaro.fr/pdf/FT/DOW_CORNING_ELECTRONICS_FT_SC102.pdf

This shows the Dow 340 is best suited for electronic parts like transistors and such getting mounted to heat sinks

https://www.spacematdb.com/spacemat/manudatasheets/DC%20340.pdf

The big thing is the viscosity and other properties listed in each PDF shows these two compounds differ greatly. ( these properties can change with time which is why they have a shelf life )

In the end it is your vehicle and your decision to make, if it was me I would toss it in the trash yet that is just what i would do.

[DerekTheGreat]

Its basically zinc oxide (sunscreen) in a silicone grease. Not much to go bad honestly so long as the tube is closed. It will eventually dry out if you leave the cap off.

This. Run it.

Even if applied when still within the expiration date the finished product would go beyond said expiration date, so that's all moot. It's not like what's inside is some living organism which dies or loses it's effectiveness over time, especially if it is unopened to start with.

[sly]

I used leftover CPU grease on one TFI module (I think it was the Mad Marquis) and I've heard of zero issues with it up until I sold it. Doesn't look like there's been any issues either since I still see it hauling ass from time to time. That was well over 6 years ago now... probably over 8 years... I'd have to go look up old posts. As long as it's rated for >125C usage... you're fine.

[gadget73]

I tend to think TFI failure is a little bit over-hyped. I thought I had a bad one on the Mark VII when it died around 230k, but it was a pickup failure. I still have the original module around here someplace. The only one I've personally had fail was an aftermarket, and it shit out the day after seriously overheating the engine from a water pump failure. Changed the pump, went to lunch, it died sitting at a stop light without any warning. The replacement is a no-name Napa module that has been on the car some 13 years now, using whatever thermal goop I had on hand. I used to buy the basic white paste from Radio Shack, so likely that. I've worked on a lot of 30+ year old electronics that didn't overheat and die from the paste being old. Replacing it after multiple decades does tend to make parts run a little cooler though so maybe consider adding "replace thermal paste" to the 25 year service list.

[slack]

This might be a stupid thought as I'm talking out my ass.

With the expiration date, say it expires in a month or so and you install with it today... and then that thermal paste sits on there like gadget for 13 years without issue. Isn't that installed thermal paste basically expired as of a month after the install?

Like I said, just asking. But if that was the case, I would think that paste would be good for a long time regardless of the expiration date. (as long as it doesn't dry out) Otherwise we would have to scrape of the existing paste after so many years and replace with fresh.

[EaOutlaw1969]

I tend to think TFI failure is a little bit over-hyped. I thought I had a bad one on the Mark VII when it died around 230k, but it was a pickup failure. I still have the original module around here someplace. The only one I've personally had fail was an aftermarket, and it shit out the day after seriously overheating the engine from a water pump failure. Changed the pump, went to lunch, it died sitting at a stop light without any warning. The replacement is a no-name Napa module that has been on the car some 13 years now, using whatever thermal goop I had on hand. I used to buy the basic white paste from Radio Shack, so likely that. I've worked on a lot of 30+ year old electronics that didn't overheat and die from the paste being old. Replacing it after multiple decades does tend to make parts run a little cooler though so maybe consider adding "replace thermal paste" to the 25 year service list.

The OP originally stated that he thinks the Dow 340 is good for thick film ignition modules which is wrong it has the wrong viscosity it will be way too thin. the age of the product is secondary and does not matter because it should not be used.

Dow 340 Viscosity cP 542,000

Dow SC 102 Viscosity cP 29000

[jaywish]

So having read what the crowd has to say..... Tell me are you going to put it on the shelf or in the trash?

[WagonMan]

I really don't need it. I have extra dizzies in case my cars break down. It'll sit on the shelf with the rest of my silicone sealers, lubricants and sealers. WagonMan