I added 2 or 3 ounces of RO water to my radiator last week, just to bring the level up to the Max line. Then I realized the leftover coolant I had on hand is 50/50 mix and I could have added some of that instead. This is the only coolant I've had to add in the last year or two, and this is of no concern right? I just wanted to add 2-3 ounces, enough to bring it up to the max line so I can see it when I rock the car from side to side when I check it. Some guy on a Toyota hybrid forum was trying to tell me I have a coolant leak, but I doubt I do. When I start the car, I can smell coolant in the exhaust, and we've talked about that here in other posts. Because the car has a sensor in the muffler or something that helps send warm air to the air intake or something like that, until the engine warms up, and then I no longer smell coolant in the exhaust.. It's been a wonderful little car for me for 3.75 years now. I'm fixing to change my oil soon, at 11 months and about 2300 miles. I finally ran this fill of oil past the 6 month mark. It was hard to get over the 6 month OCI habit. With Pennzoil Platinum full synthetic 0w20, I could probably wait until Spring or even Oct 2024 and be fine. It still makes the engine purr like a kitten.
Doesn’t sound like an issue, but keep an eye on it. You shouldn’t be losing coolant consistently. Regarding smelling coolant in the exhaust, that doesn’t sound right to me
