Coolant leak

The short version

Slow drop

You can ride it out for a while. Top off and watch the level.

Stop driving if

The reservoir runs very low or the temperature gauge climbs. Overheating can blow a head gasket, which turns this into a far more expensive repair.

Expect it

It's a known weak spot on the GX460's V8, and it usually shows up after 100k miles. Mine had it.

Rule out first

A worn radiator cap or loose coolant fittings can also cause slow loss. Both are cheap to check.

Confirm it

A shop can look into the engine valley with a borescope. Coolant pools there and runs down the back of the engine, which is why there's no puddle.

The fix

Replace the valley plate gasket. The intake has to come off, so most of the bill is labor. Get two quotes. $1,400–$2,000 is fair; around $4,000 is too high.

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