My Subaru started overheating; it had run out of coolant completely.

Once I refilled the coolant, the car ran about a 1.2k mile trip just fine without any overheating.

Recently, the car started doing it again.

I have to periodically open the radiator and dump more coolant in every 300 miles or it will begin to overheat.

Unfortunately, the time has come where I have to drive 1k miles.

I have a new car waiting for me at the end of that 1k drive and all I need to do is make this trip.

Any other alternative will be $1000 atleast; replacing the head gasket at a mechanic is $1700.

No mechanic has actually looked at the engine, so I'm just assuming this is a head gasket based on the symptoms and the fact that is has overheated previously.

What's the best course of action?

Is this something that is urgent and needs to be fixed right away?

Can I use Subaru Coolant System Conditioner to seal the leak?

Note: I don't care if I obliterate the engine by getting there. The car is almost scrap at this point having nearly been totaled with repairs.

  • 2
    Practically speaking, if you're really concerned about making the 1K trip, and you don't have the time to fix the vehicle yourself or it's too expensive, and getting stranded on the way is unacceptable, it might be cheaper to do a one-way car rental for a day.
    – Jason C
    Aug 9, 2016 at 2:26
  • 1
    I agree with Jason. I recently flew out to buy a used car. A last minute ticket cost me $350, and 8 hours after takeoff I had bought the car and begun the 1700 mile return drive. If you decide to drive out, best case scenario is you spend 16+ loud, uncomfortable hours in the Scooby, pulling over to check the cars vitals every 90 minutes, all the while wondering when the car will finally kick the bucket leaving you stranded in no-mans land. Then you finally get there, deal with the dying Subaru carcass, and hop into your new but unfamiliar car to drive 15+ slightly less stressful hours back. Aug 9, 2016 at 14:20
  • @JasonC I totally would if I was 25... The other option would be a Uhaul which charges per mile. Pretty rough Aug 9, 2016 at 19:00
  • 1
    @MooseLucifer I agree. One thing I didn't mention is I don't need to drive back. I'll be staying there. I will still not drive the subie sounds too dangerous Aug 9, 2016 at 19:03
  • 1
    Good call, especially if it's a part of a move. Wash your hands of the tired old workhorse and start your new life! Also consider donating the car to charity, Assuming you're in the states, I know National Public Radio will tow it away for free, and you can deduct the cars (modestly inflated) value from next years taxes. Aug 9, 2016 at 19:09

2 Answers 2


What's the best course of action?

Figure out where the coolant is going. Here are some ideas:

  • Drain your oil and change it, and the oil filter too. Look for signs of coolant in the old oil. If you see coolant there, good chance it's the head gasket.
  • Check your exhaust for white smoke. If the engine is burning coolant, good chance it's the head gasket.
  • If there's no white smoke and none in your oil it has to be going somewhere. Go down to your local auto parts store, grab some UV coolant dye and a UV flashlight (you can usually buy leak detection kits with a cheap flashlight and eye protection) and throw it in. Run the engine. Look for signs of coolant leaking. The dye will make it easier to see. If you're losing coolant around the exhaust manifold good chance it's the head gasket. But it could be coming from other places. Be sure to also check inside the passenger compartment, particularly on the floor under the dash. If there's coolant there it could be the heater core.
  • When checking for coolant leaks, park over top of something that won't absorb (and therefore hide) puddles, and rev up the engine. I learned this the annoying way (btw, if it gives you hope, that issue ended up costing < 90 USD in parts and about 20 minutes in labor).
  • Also check your coolant reserve tank; if it's overfull (like all your coolant is ending up in the tank but not making it back into the radiator) could be an issue with the tank, some hoses, or perhaps the radiator cap.

Is this something that is urgent and needs to be fixed right away?

Depends on where it's leaking from and how costly and inconvenient it is to constantly be dumping coolant into your tank. Also the more you overheat your engine, even if you stop driving right away, the more you risk even more (and expensive) damage. I definitely wouldn't drive it 1000 miles...

More importantly, even if you don't care about the car, you run this risk of being stranded somewhere if the vehicle breaks down.

Can I use Subaru Coolant System Conditioner to seal the leak?

Maybe? I'm not familiar with that product but apparently it is a relabeled version of Holt's RadWeld, which seems to get a decent amount of praise all over the internet.

Without knowing where the leak is it's hard to say. It probably won't hurt but it may not help. I've used similar products (the Prestone stuff) with success for tiny leaks but losing all your coolant every 300 miles doesn't seem tiny.

Your first step is to find the leak.


I agree with the advice given by an earlier correspondent: Seek alternate forms of transport, to get yourself to the new car which awaits you. You risk stranding yourself, and having to deal with junking your old car, in an unfamiliar location, in the middle of a trip. Take a bus, or a train; rent a car, or fly. Your old Subaru is not worth fussing with, since you have a new car anyway. You've got a classic blown head gasket (2.5 engine), and maybe head warpage.

  • 1
    Agree. And then when you get home, sell the Subaru. There are lots of people out there who would love to buy your car (with broken engine) and then drop a second-hand engine in it to make it run again - Head Gaskets are that prevalent in that age of Subaru.
    – PeteCon
    Aug 9, 2016 at 14:38

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .