Put 5w30 in power steering reservoir

2000 Blazer 4wd, 113k miles. I grabbed the wrong bottle and put about 8-10 oz of oil in the reservoir.

Unfortunately I ran the engine for a few minutes. I didn’t turn the steering wheel so I’m hoping most of the oil stayed in the reservoir. Currently draining and refilling with PS fluid tp get as much of the oil out as possible before I take it to the mechanic for a flush.

Anything else I can do?


Ed B.

Even without turning the wheel the fluid circulates throughout the system but no damage is done. Power stearing fluid is oil based but much higher viscosity and without the anti foaming agents. If you remove the return line from the reservoir, cap the connector on the reservoir, point the return hose into a bucket, start the engine and let it idle while pouring a couple of quarts of P/S fluid into the reservoir, then reconnecting the hose and topping off the fluid all will be well again.

Motor oil and ATF are compatible. It won’t hurt anything. The motor oil is a little too thick to be left in the system…

Thanks for the replies. Unfortunately the only way to get to the PS pump is to remove the radiator or put it up on a lift. The pump is buried underneath the AC compressor .

I used a siphon to drain the fluid out of the reservoir. On the first attempt the fluid was clear and thick. I believe this was most of the 5w-30. I refilled with 10 oz of PS fluid and repeated the process until I ran 2 quarts through the system. This time the drained fluid was darker and thinner than the first time. The fluid got lighter each time as more fresh PS fluid was put in the system.

Ed B.

When turning the wheel while the vehicle is not moving, especially if the wheel is turned to its limit, the fluid will tend to cavitate and foam, making it more difficult to turn the wheel and causing the pump to become moisy. The correct fluid is less likely to foam. If the fluid in your system is very similar in color and viscosity to the correct fluid you likely have everything back in good order.