Drove Prius 4 to 10 miles without oil! Was there damage?

The oil was changed by a highly reputable shop 2 days ago, (45 miles ago). My wife noticed today that the “Low Oil Pressure” red message flashed 3 times in the last 5 miles of her 10 mile trip (45-50 mph). She stopped the car and called me. I arrived at the parked Prius and saw no oil on the dipstick. I poured a quart of synthetic in and looked under the car to see it pouring out. My finger discovered that there was No Oil Plug. I called the shop and they sent a tow truck, put a new oil plug in, refilled the oil and claim no damage since “the Prius shuts off the gas engine when low oil pressure is sensed”. Can anyone lead me to information about this “shut off feature?” What should I ask from the shop? What should be tested & checked for? How do you test for damage to the bearings? How about a compression test? The car has 100K miles. Thanks !

The “shut off feature” is the engine seized up.

There is damage to the bearing etc however it if it is running difficult to come up with something.

Does the paper work mention missing drain plug(make sure) in case you soon have to return to repair/replace the engine. That is why in such situations it is actually better to send car to dealer since they are third party in a potential dispute.

I hope it works out for ya.

If there was a low pressure sensor the engine would have shut off almost immediately, not in 5 miles. Document as much as you can. See if your Toyota dealer can give you information on the alleged low oil sensor shut off circuit. Your engine has been damaged. It may run OK now, but in the future you will start to see symptoms showing up.

There is damage and they’re feeding you BS so as to get you down the road while hopefully buying enough time to absolve themselves of any responsibility.

A dry/wet compression test and oil pressure test with a manual gauge could be performed. That may reveal some problems.
Some problems are not detectble without physically disassembling some things.

GM is the only one I know of that used an oil pressure operated fuel pump but that was a long time ago and is not used any longer.
They’re just trying to blow you off to aid their own bottom line. It’s entirely normal to do this.

I agree with the others and think it bears mentioning that a “highly reputable” shop would not lie to you in a transparent attempt to get out of responsibility for damage that they caused.

I am going to agree with the shop. I have seen a few Prius where this has happened at quick lube places and the engines were fine. Tear down for inspections surprisingly showed no damage. I would ask the shop to pay for an oil analysis now and at your next oil change or remove the oil pan and inspect for bearing material. How does the engine run and sound?

Was this a “highly reputable” iffy lube. I ask because any real reputable shop would not have used the low oil pressure shut off line. Especially to some who already drove the car about five miles after the warning light came on.

Yes, there is damage. Get to a lawyer who can advise you how to document what happened and sue them for the damages they caused. Rocketman

This is APPALLING ! If there actually IS a magic shut off for lack of oil pressure…then you will probably be ok…if NOT…I would have to agree with the others.

What do I know…I’ve only been doing engines for 28yrs now. I’ve seen engines live that shouldn’t and Ive seen engines die when you wouldn’t have thunk it. Sometimes the more I think I know…the less i do…lol

Im convinced its the Humans involved that provide the crazy variables


We have a 2012 Prius. I back out of garage and first 10 ft is elec mode. Gas motor starts at 20 ft? I have tried hitting EV mode button when I backup and I get a message saying EV mode is not available. Have no idea what computer will do with gas motor and low oil pressure situation.


The computer in your Prius will shut the engine down if it detects the oil pressure is too low, and switch over to the electric motor.


Some industrail engines have a low pressure shut off(Murphy Switch) but dont think most cars do,however a lot of them will shut off if they are overheating(trucks will anyhow)Now if new cars are not so equipped it puzzles me ,as to why.I would say there is some damage,but probaly not as much as you would think,the big problem is if the crankshaft journals and bearing material made physical contact,because of lack of oil pressure.Why did she take so long to notice the oil pressure light was on? And perhaps if the oil pressure light took so long to come on,maybe the drain plug was in there,when the car left the shop-good luck,hope your engine is ok

Finally a vehicle that can think… Nice.


So, if you don’t fill up with oil, your gas mileage could actually be better :smiley:
Amazing stuff. The Prius is Jiffy lube proof.

Thanks Tester for the link wanted to post the info on the oil pressure cut earlier but did not have time. Between the oil cut and having inspected engines where this has happened before and seen no measurable damage, I think the OP would be safe having the oil analysis done and proceding from there.

Engine may or may not be damaged. If the fail-safe worked, could be ok. In any event OP should at least send a certified letter to the owner of the shop that did the oil change documenting what happened. If the gas engine develops symptoms later, you’ll have something on file to work with.

Agreed. IMHO I bet this persons engine will be just fine in the end. George and others make a perfectly valid suggestion however. I would follow their advice, fill that engine back up and motor on…if any oil related issues occur with the engine in the following yrs…you have proof of this incident as some possible insurance perhaps?

I think this engine will be OK…the Prius…unlike Humans doesn’t argue with itself and say if I can just make it to the next exit I will pull over and shut it off.


I would go to a dealer, the service manager, and verify that the gas engine shuts down in the event of zero oil pressure…More than likely, the plug was installed finger tight but never tightened with a wrench…So the actual distance driven with no oil is open for debate…Had they not replaced the plug at all, the light would have been flashing when you drove away from the shop…

No drain plug and no oil would tell me the Prius safety system does not work very well if the car went 4 to 10 miles like this. That’s more than enough miles to damage an engine.

The more time that elapses between this incident and a noticeable (key word) problem cropping up just means that it’s more and more difficult to hold someone responsible for their faux pas.

Low, as opposed to zero, oil pressure does not mean the oil pressure is sufficient to prevent engine damage. When a boxing match is going on between 1500+ PSI of cylinder pressure duking it out with 5 PSI of oil pressure on a thousandth of an inch of oil clearance on the crank bearings the former is going to win; either by decision or by knockout.

@ok4450 … Confused a little by your post. In the event of a low oil condition, couldn’t the Prius have traveled 4-10 miles just using its electric battery powered engine, never needing to start the gasoline one?