I was wondering what would be the best antifreeze to top off my 1991 xjs with? It’s a v12. Thanks

 

I've always used old fashioned green anti-freeze, Prestone or NAPA house brand, in my Jags. I duuno if that's "best", but nothing bad has ever happened.

What's in the system now? If you have any reason to believe the system has been filled with some other formulation (DexCool, for just one example) then you won't want to mix different types.

Cheers
DD

 

I’m not sure what was previously used, so with that being said what’s a safe option? Thanks

 

Drain and refill with new. You can get antifreeze that will mix with any sort. safely.

 

As Greg has said, a good time to drain the whole lot and replace. If you're not sure what's in there, it sounds like it hasn't been changed for a few years, so needs replacing.

If it's green / blue, the chances are that it's the older IAT f(Inorganic Acid Technology) fluid which probably has silicates. If it's red, there's a chance that it's OAT (Organic Acid Technology) which is probably silicate free. You don't want to mix those two.

Once drained and flushed through , if you're really not sure what was in there, maybe fill with a HOAT (Hybrid Organic) which should be ok whatever was in there before.

Paul

 

problem is I want to take it to my mechanic and it’s noticeable low and I don’t want to risk driving it to him without topping it off. Is there any safe option for this problem?

 

For a short trip after which he's going to drain and flush the system, just add distilled water. This assumes it's not freezing outside. If it is below freezing, add any quality antifreeze plus distilled water in a 50/50 mix, or buy pre-mixed.

 

would this be ok?

 

Watchguy,

As your mechanic is clearly going to drain the whole lot out and refill it properly. just top it up with distilled water. It'll be fine

Paul

 

Thanks for the help.