2005 BMW X5 3.0i Sport
I just happened to check the coolant and it’s so low to a point I can’t even see it. I normally get a warning on the dash telling me to check the coolant level. I was told that I have to completely drain the old coolant before adding new but I’ve never done it so I just filled it (coolant: distilled water 50/50) since I need to drive this morning and didn’t have time to take it to the shop. Is this ok or should I have it drained as soon as I get a chance?
Was the coolant ever changed?
If not, it is seriously overdue for changing, as the rust inhibitors in the coolant become depleted after just a few years.
However, the more pressing issue is the question of why your coolant level was so low.
You need to get the car into the shop in order to have the cooling system pressure-tested for leaks.
If that test doesn’t provide a clue to the dangerously low level of coolant in the system, then you have to do other tests in order to find out if…for instance…the head gasket has been breached.
About every five years, you need to have the cooling system drained and refilled with fresh coolant. Your coolant contains corrosion inhibitors that protect your engine, these last about five years in the new antifreezes that are on the market.
You do not need to flush the system if you follow this schedule. A simple drain and refill does not get 100% of the old coolant out, but it gets most of it and the refill will put enough new corrosion inhibitors back in to last another 5 years. It is important to drain the block as well as the radiator. An oil change does not get all the old oil out either but you don’t flush the engine at each oil change.
If the coolant gets low between changes, you simply add coolant, just the same as you do with your oil. Normally you would add little to none between changes so if you find the system low and have to add coolant on a periodic basis, you need to look for a leak.
Coolant leaks start off as small leaks, but have a habit of becoming massive leaks on very short notice and that can result in major engine damage. I am not trying to scare you but, you probably should get the system pressure tested for a leak and if you haven’t had a coolant system change for 5 years or more, or if the coolant appears cloudy or brown, have it changed after the pressure check.
You may also need a new radiator cap if no leaks are found. Even if a leak is found, you may need one anyway. Personally at ten years, I do a major cooling system maintenance by draining the whole system, replacing all the radiator hoses and heater hoses and the radiator cap, then refill with fresh coolant. After ten years, a hose can blow out with no notice and cause damage to the engine.
I might point out something disturbing . . .
Many manufacturers say the factory fill coolant is good for 10 years, then it gets drained and refilled
After that it’s good for x number of years/x number of miles, whichever comes first
I agree with the second part, but that 10 year thing is seriously misguided and/or optimistic, in my opinion
I’ve owned several cars which also made such claims. But I always changed the coolant after 3-5 years, depending on the brand and type of coolant
I guess it’s on the lines of “lifetime” atf . . .
Or valves which don’t need adjustment, if they’re not noisey . . .
No harm done to top it off to get you to work, but performance cars especially can be unforgiving of cooling system problems, or the use of the incorrect coolant type, so take it to a qualified shop as soon as you can, someone that has experience working on BMWs, and get the cooling system inspected and the maintenance brought up to date.