coolant suggestions?

[jbutler67]

1986 Rampage 24 Express with
Mercruiser M048938 (5.0L)

Suggestions on what to use for coolant in closed cooling system? Previous owner was using Napa Orange (see picture).

Thanks

 

[Bt Doctur]

If unsure what is in there do a complete flush with water a few times and then refill with what you use.
There are reports of mixing with dex-cool products that will turn the A/F into a gel

 

[harringtondav]

I'll stir the pot by saying that automotive antifreeze/coolant is all the same, mostly made by one mfg. Just use automotive ethylene glycol. The pink RV antifreeze is OK for winterizing water systems and drains, but no good in engines.

 

[Bt Doctur]

I guess you never have seen a gas tank turned into jello or an engine block and heat exchanger with pink jello either

 

[harringtondav]

I have not seen the gel. But other than flushing solutions, I've never put anything into a closed engine cooling system but 50/50 pure (no snake oil) antifreeze/coolant and water. I've assumed a marine heat exchanger is just a seawater cooled radiator, but I'm still ready to learn. I've seen ATF or hyd. oil and coolant swap spit in some heat exchangers, but never gasoline and coolant.

 

[Scott Danforth]

Dont mix green and orange..,,turns into brown sludge.

What is wrong with running the same that the PO ran?

 

[fishrdan]

Use the Napa Orange stuff, or it's equivilant. Different coolant technologies can react and cause problems.

My current truck, someone serviced it with "green" antifreeze before I got it, truck would borderline overheat towing, entire cooling system had a white coating. Long time consuming process to clean up that mess... After cleaning up the cooling system, runs cool as a cucumber.

 

[achris]

I'll stir the pot by saying that automotive antifreeze/coolant is all the same, mostly made by one mfg. Just use automotive ethylene glycol. The pink RV antifreeze is OK for winterizing water systems and drains, but no good in engines.

Err, no... Ethylene glycol and OAT coolants are definitely NOT compatible. If you have one, it's a MAJOR ball-ache to clean the WHOLE system out before putting the other in... ANY left over and you have an ungodly mess to deal with...

I have red coolant in the cars, and green in the boat. The red coolant lives in the garage, by the cars, and the green only in the shed, by the boat.... See, I even keep them in separate locations to avoid a mix up...

Chris......

 

[jbutler67]

Thanks all. I learned two things from this thread
1) ethylene glycol only
2) don’t mix colors

I drained the block and think I have all the old coolant flushed out of block and heat exchanger, but it’s not worth the risk. There’s really no need to change to different coolant.
I’ll stick with the Napa Orange. 50/50 mix.

Very much appreciate the great advice on this forum.

 

[harringtondav]

Err, no... Ethylene glycol and OAT coolants are definitely NOT compatible.

Chris......

Medicare in December, and Im still learning. What is OAT?

 

[AlabamaNewbie]

OAT - organic acid/additive technology. These are coolants that say they are non-toxic, such as DEX-COOL. They do not play nice with ethylene glycol based coolants (IATs). When mixed, they form a sludge/gel that can block off water flow through the jacket. Not immediately, but over a relatively short amount of time.

For example - when they put regular coolant in my patrol car previously filled with dex-cool, it took 3 months of hard driving, but eventually it happened that I began overheating. They wouldn't listen to me when I told them what the problem was. They replaced fans, hoses, thermostats, and by the time they listened, it was bad enough that the entire radiator had to be replaced and the entire cooling system flushed many times to clear it. It's a miracle it didn't warp a head.

 

[achris]

Medicare in December, and Im still learning. What is OAT?

On a aeroplane instrument panel, it's Outside Air Temperature....

 

[southkogs]

On a aeroplane instrument panel, it's Outside Air Temperature....

Great ... now what's an "aeroplane?"

 

[achris]

Great ... now what's an "aeroplane?"

Sorry, in 'Merica.... airplane.

 

[southkogs]

Frankly, I think it looks/sounds much more enticing the way y'all spell it. Much like the word colour.

I also get a laugh out of the way they get described as "airplane and aeroplane are different spellings of the same word. Airplane is the preferred spelling in American English, and aeroplane is the preferred in all other forms of English."

 

[Lou C]

like a spanner, bonnet or a boot eh?
as far as coolants, you can use whatever you want but stick to one type of additive pack once you decide. For example, Ford and Chrysler used HOAT antifreeze (available in the aftermarket as Zerex) whereas GM used OAT (Dexcool) both of these replaced the traditional old green stuff we used for decades. The new antifreezes are supposed to last longer but you should probably still change them at 5 year intervals. Personally if you are using one type in your vehicles, then why not use that in your closed cooling system, I have had good luck with the Zerex in the Jeeps with minimal cooling issues over the years. You could also use Sierra no tox propylene glycol AF if you are concerned about a leak putting AF into your bilge water, but the freeze up and boil over specs are not as good for the PG antifreeze as they are for EG antifreeze.

the biggest issue today is that the OEMs are contributing to the mass of confusion on antifreeze types. They all recommend their own 'specialized OEM antifreeze' without telling you just WHAT it is! I was never able to get from Subaru what type of antifreeze they used so I used their OEM stuff in our old '98 Outback for fear of causing cooling problems if I used the wrong stuff. At least on the Jeeps I was able to find out what the OEM specified and use the aftermarket version of that. So the OEMS don't tell you what their formulation is and if you have to add antifreeze in the field (due to a leak, bad cap, blown hose etc) you are left guessing.

 

[HT32BSX115]

Sorry, in 'Merica.... airplane.

Yes! And my Kiwi Son-In-Law INSISTS our outdrives are constructed of Aluminium too! (NOT Aluminum!!!)

 

[Lou C]

There is some concerning mis-information in this thread:
OAT (Dexcool) and HOAT (Zerex) antifreezes are both ethylene glycol based and are VERY TOXIC!
The only non toxic stuff you can use in an engine that I know of is Sierra which is a totally different chemistry (propylene glycol) similar to RV antifreezes.

 

[Lou C]

The main differences between the old green and OAT and HOAT are the additives added to make them long life coolants. They are all ethylene glycol based.

 

[achris]

Yes! And my Kiwi Son-In-Law INSISTS our outdrives are constructed of Aluminium too! (NOT Aluminum!!!)

Yes.