Penrite has wrong coolant listed for WH 2005-2011 diesel

[bjm]

Have been in on going contact with Penrite re correct coolant for WH diesels.Firstly the WH owners manual states the coolant should be a HOAT product not OAT as per Penrites listing.Plus WH years should only go from 2005-2010. Year 2011 was when the new WK2 plus Fiat motor arrived ,it should be OAT ,not be HOAT both my 2010 and 2011 have been for a while running the wrong coolants !! (If a vehicle has been running the incorrect coolant and the correct coolant is added without a flush gelling might occur.) I might add I have had no issues. Penrite has stated that the coolant is made by an outside company to Jeep specs.Currently they are looking into it with some urgency.I have not looked at other companies spec sheets . this was a number of weeks ago.!!

[JamesLaugesen]

Many fluid manufacturers/retailers listings have mistakes, not just for Jeep. The only way to be confident is to read/understand the individual specs.

Coolant specifically is a bit dodgy, as there's no standardisation in the specs or how they're published. IMO only way to be safe is to never mix coolants, even if both OAT or boath HOAT, etc.

[Brit30-06]

Hi
For what it's worth I have noticed that UK jeep dealers now put the OAT coolant in our WH. They have dropped the HOAT stuff.

What do Mercedes spec for its OM642 engine? HOAT or OAT?

I had wondered if Jeep had specified the HOAT for the CRD to just keep Coolant compatability across the whole jeep range rather than actually needing to. A little like deciding to put ATF4 in the Jeep's Mercedes transmission.

[bjm]

Had an ambiguous reply back from Penrite yesterday re coolant type.Asked them to clarify if any difference between 2005 -2010 Merc motors and 2011 on Fiat .Stated all Jeeps may be now using Hoat. Will see what arises.

[MidnightMods]

Who stated all jeeps may now be using HOAT?

I think its the wrong away around.. HOAT is the jk crd stopped and went to OAT when the emission change build in 11+

[bjm]

Thats why I am questioning Penrite s info .I might add this info is comming from the head technical guy in P Australia

[JamesLaugesen]

Not that it really helps, but the difference is just that an OAT formula can't contain silicates or phosphates (as corrosion inhibitors.) while HOAT formulas do.

The only downside of using HOAT when OAT is spec'd, is that the silicates and phosphates can gel or just fall out of suspension and loose effectiveness. That's a risk for manufacturers considering the number of vehicles which never get a coolant change.

But for us with maintenance up-to-scratch I recon HOAT is always the go.

It's plausible FCJ could've changed the spec from HOAT to OAT (or even back again?) just based-on risk of corrosion vs gelling with lack of maintenance, but it probably doesn't mean much for us either-way.

So IMO you can safely stick to the HOAT... and only ever top-up with distilled water obviously.
If you think the coolant might've already been mixed, you'd need to do a full flush to know for-sure that it's safe regardless of the spec (although I wouldn't bother.). Since compatibility is more about the precise formulas (which we have no way of knowing.) regardless of HOAT, OAT or IAT.