Jeep Patriot Forums banner
Cancel
Create thread New Garage Forums

OAT vs HOAT - Patriot Coolant Conundrum?!

Jump to Latest
6K views 4 replies 3 participants last post by  PatriotUK  
#1 ·
I may well have posted a topic regarding coolant before, many years ago, but this is a question where I desperately need some clarification....

A background to my Patriot (2.2L diesel):

When I bought my Jeep 4 years ago, I noticed that the coolant colour in the reservoir was orange/red/pink.

Over the following years, the car displayed a very slow and intermittent coolant leak. It had had the water pump changed at 35K I believe (looking at service history) and it was on about 90K when I started to notice very gradual coolant reduction. Anyway, I got Jeep to flush my coolant 2 years ago (thinking I may have the "wrong" coolant in there), and I bought myself some Xstream G05 HOAT coolant (what the manual says and what official sources online say is correct for my Patriot.) This coolant is more yellow/gold in colour.

Anyway....over the last two years, the coolant leak continued to be fairly gradual until just over 1 month ago it rapidly sped up. So as I said in a previous topic recently - I got it serviced and repaired - and the lower radiator hose had corroded and it was leaking there. This is now fixed.

Here's the thing.....upon getting my car back the other week, I noticed the coolant is now red/pink again 🤣 I have 3L left over of G05 too, which is annoying! But I know mixing coolants is generally a no-no. I've done a lot of research into this.

The mechanic told me it's longlife red coolant and gave me the code number for product. It's an OAT coolant. I also asked Jeep main dealer (who I do not use) what coolant they would use on a Patriot out of curiosity, and they confirmed that they use a red antifreeze (OAT) for Jeeps up to 2015.

So, what is the best coolant to use in a Patriot, a 2011 one like mine to be precise? I've read forums where some people say you can technically mix HOAT and OAT, and other people say it's a risk and things may turn "to sludge?!"

I've also read that you can use OAT coolant in an older (but not too old) HOAT cooling system, but you can't use HOAT coolant in a more modern OAT cooling system....?

Can anyone give me any further clarification here? Thanks
 
T
#2 · (Edited)
Short answer - looks like you are supposed to use HOAT that meets spec. MS-9769 according to my 2014 factory service manual. Your mechanic did not follow OEM recommendations. They should flush and replace it for free, UNLESS THEY SHOW YOU A TSB STATING OTHERWISE.

Coolant choices have become insane. You definitely do NOT want to ever mix OAT and HOAT because they can form solids (gel). We had a member here post not too long ago about losing his engine due to mixing coolants.
  • Coolant color means nothing now-a-days.
  • If you cannot determine what is in your engine now, you will probably have to flush all the current fluid out and start over with a recommended product.
  • Diesel engines "can" require special additives (SCA) if they have wet sleeves in order to prevent cavitation. I'm not sure about the Patriot 2.2L diesel.
  • Some OAT coolants still contain a plasticizer called 2EHA that can harm engine gaskets not designed for it.

My 2014 factory service manual says this about the 2.2L diesel:

"DIESEL ENGINE
The cooling system is designed around the coolant. The coolant must accept heat from engine metal, in the cylinder head area near the exhaust valves and engine block. Then coolant carries the heat to the radiator where the tube/fin radiator can transfer the heat to the air.
The use of aluminum cylinder blocks, cylinder heads, and water pumps requires special corrosion protection. Mopar® Antifreeze/Coolant, 5 Year/100,000 Mile Formula (MS-9769), or the equivalent ethylene glycol based coolant with hybrid organic corrosion inhibitors (called HOAT, for Hybrid Organic Additive Technology) is recommended. This coolant offers the best engine cooling without corrosion when mixed with 50% Ethylene Glycol and 50% distilled water to obtain a freeze point of -37°C (-35°F). If it loses color or becomes contaminated, drain, flush, and replace with fresh properly mixed coolant solution.

CAUTION:​
Mopar® Antifreeze/Coolant, 5 Year/160,000 km (100,000 Mile) Formula (MS-9769) may not be mixed with any other type of antifreeze. Doing so will reduce the corrosion protection and may result in premature water pump seal failure. If non-HOAT coolant is introduced into the cooling system in an emergency, it should be replaced with the specified coolant as soon as possible. "​

Zerex GO5 is an approved HOAT fluid to replace MOPAR MS-9769 spec. and it is suitable for diesel engines.
 
#5 ·
Sorry I never responded to this, it was about one week before I travelled to Scotland and was doing a lot of last minute planning. I did read your comment at the time though, and appreciate your advice!

It does indeed say in my manual that I should be using a HOAT coolant. It's now been three months or so with the OAT coolant holding steady and the car driving fine, although I am conscious HOAT has better anti-corrosion properties.

I could ask the guy who services my car to flush it again come fall this year, but I don't really know whether it's truly worth it? Either way, looks like my local jeep dealership don't follow OEM recommendations either. I already bought just 1L of new coolant in case any leaks ever develop. I tend to carry that, spare oil, a diesel can and a load of tools round with me, as I take my jeep all over the UK and drive off-road into the woods and go wild camping.

"Some OAT coolants still contain a plasticizer called 2EHA that can harm engine gaskets not designed for it."

Perhaps worth checking with the company I bought coolant from?
 
Jeep Patriot Forums
posts
679K
members
55K
Since
2006
Join our community to discuss the Jeep Patriot & Jeep Compass. Find answers to all your Jeep Patriot technical questions.
Full Forum Listing
Explore Our Forums
Jeep Patriot General Discussion Engine and Drivetrain Newbie Check-In Suspension and Tires Electrical and Audio