Skip the auto shop - Our mechanics make house calls

Q: Idles up, burns 1 quart oil every 20sec with no oil leak.

asked by on

Hi there, my father in laws Bonneville blew the plastic portion of his oil sending unit clear off the 1 1\16" thread nut and we replaced it. After that I discovered the car he's ownered for 2 years had not seen an oil change in 8 years total so we did that. Then we got a low oil pressure read on the dash and saw smoke coming from the the engine right valve cover. When we killed the motor and opened the oil fill cap on that valve cover, we heard a relief of back pressure come from thru out the whole motor. I replaced the PCV valve today and checked the oil again and it was close to the max oil level. I started the vehicle and after idling down the normal operating RPMs the car, on its own started to increase rpm from 1,100-1,600rpm and a whining internal noise became gradually louder as the RPMs rose. I killed the motor and checked the oil and it was now at the minimum film line, about 1 1\2qrts down. I don't know if the rings finally gave or what but there are no leaks or dripping.

My car has 213000 miles.
My car has an automatic transmission.

A: You might not have burned that much oil in ...

You might not have burned that much oil in 30 seconds of running the motor but the oil is not draining back from the upper parts of the motor. The sludge that has built up in the motor has clogged the return drains in the heads and oil gets trapped up in the valve covers. You should look in one of the valve covers to see if the engine is sludge blocking drains in the heads. If it is then you may have to clean out both valve covers and heads of sludge and then run cleaner through engine several times to remove some of the sludge build up. If this does not help then rebuilding of the motor is only option.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: Ignition key replacement on locked car.

Hi there. If the key is stuck in the ignition then the ignition lock cylinder is either bad or you have a dead battery. I would test the battery first and see if that is the problem. If the battery...

Q: Will 01 grand am wheels n tires 205/55r16 fit my 91 Bonneville?

I am pretty sure GM did not change the bolt pattern between these two year of vehicles. As a precaution, count the number of lugs and measure the length between the lug studs and compare it on both wheels. Make...

Q: To check the transmission oil on my pontiac g6 do it has to be running, it dosent have a dipstick so i have to take out the bolt

You have to have the engine running on a lift or a flat surface before you take out the check plug or else the fluid will spill out. Then you can check the fluid level and put the plug back...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...