Oil Consumption Question

Dom makes a good point - there is a significant difference between oil "leaking" and "oil consumption". You mentioned both - consumption in the topic title and leaking in your post. Is the car actually doing both, leaking and consuming the oil? Or is it just consuming oil?

As for piston soak, that is a continuous process - not a one time fix. Assuming this is oil consumption - at this rate, I'm quite surprised that a soak did anything at all.

As for the oil levels, you are letting it drop TOO MUCH. You need to keep topping off the oil, try and keep the level no lower than 1/2 quart if possible - definitely no less than a quart (look at the marks on the dipstick - between low and high is approximately a quart).

As for oil change - it is not the oil you should be worried about, but the filter. Since you have such a high rate of replenishment - I'd just drop the filter and screw on a new one. You'll lose a bit of oil in the process, just top off. If that is too much trouble, then just change out the oil like normal.

Since you are at the level of quarts per 100's of miles - depending on what the car is doing - leaking or consuming oil. Definitely start looking at a minimum of an engine rebuild, engine swap, or dump the car. Piston soaks, high mileage oils, etc. - those are just temporary measures at the moment, eventually you'll run into the case where nothing will slow the consumption of oil. If the engine is leaking oil - that is a different matter all together, but since the levels are dropping so quickly - it will eventually lead to engine damage.

Topping off the oil to keep the levels at full is absolutely critical. The sump will only hold ~4 quarts of oil. If you don't keep an eye on it and drops a quart of two in oil, that means the remaining oil has lubricate, clean, and cool the internals of the engine. Lot to ask a couple of quarts of oil to do. This won't "fix" the problem, but you can keep running the car for a very long time in the meantime.

Intermittent oil consumption is heavily driven by how the car is driven. Makes sense that the less she drives it - the less oil is being consumed. But the levels you are seeing, that drop two quarts in less than 500 miles - you are in the extreme oil consumption range. Meaning engine additives at this point are a waste of money, looking at physical repairs to stop oil consumption.

Carbon build up on the piston crown is pretty normal - every car will have that. The key is what he means by "a lot" of carbon build up.

When they did the piston soak - what chemical did they use, how did they do the soak. Many need to have the car sit overnight or more to allow the solvent time to penetrate and eat away at / loosen the deposits.

If they did this fairly quickly, likely they did a top end cleaning - that only helps with removing carbon deposits in the combustion chamber and on the top of the piston (crown). Some of these top end cleaners also run though the injectors, cleaning them at the same time as they are cleaning the combustion chambers.

IMHO - at this point - doesn't matter what oil you use, you need to make sure the crankcase is full as often as possible.

Oil changes - still need to change the filter at your original interval, no matter what is happening with the oil and frequency of makeup oil. If you want to change the oil and filter at your current interval (5000 miles) - that is perfectly fine. I understand that you might feel the oil life is OK, since you are refreshing it so often with makeup oil - but the bottom line is that you still have the change the oil and oil filter at some point.

Probably more convenient to just do a regular oil and filter change every 5K miles. Trying to change just the filter with a full crankcase is tricky for even seasoned DIYers - would save time and effort in the end to just change it out like normal.

"Why does the car burn oil the more you drive it and burn less the less you drive it" - you're kidding me about this question right? This is just operational common sense. Oil consumption is directly tied to engine usage - the longer the engine is running, the greater the likelihood that it will consume more oil during operation. If oil loss is happening only when the car is not driven as much, then this will indicate a physical leak - at this rate of loss, should make for a considerable leak spot on the floor.

Piston soak - sounds like a typical procedure for piston soak. Still, that doesn't tell me what solvent / product they used. Draining the product out is unusual - usually the solvent will seep past the rings and be in the crankcase oil, or if it didn't - they usually run the car to burn it off. Possible that they added more solvent than usual, and needed to siphon it off to prevent hydro-locking the engine.

If they used something like (MMO) Marvel Mystery Oil - that won't do much to dissolve carbon around the piston rings (can't get too it, too viscous), but will help with carbon on the piston crown (does not influence oil consumption). If they used something considerably less viscous, like Berryman, Kroil, petroleum based light solvent - those "could" get at the rings and oil drainage holes. Drawback is they have to keep track of how long it was soaking, as those solvents can be quite corrosion to internal engine parts. Berryman, for example, will eat aluminum after a length soak.

To me, piston soak = 5 weeks no consumption could be just coincidental. Sounds like the car is intermittently consuming oil depending on engine load. People who have experienced excessive oil consumption have reported that the engines seemed to be running perfectly, oil levels in check - then almost overnight, oil levels dropped a quart or two.

As long as you keep the crankcase full - car could run for a very long time. You'll likely foul the catalytic converter and O2 sensor / AFR sensor, from the excessive oil consumption, way before the engine expires.

You oil consumption is at the engine rebuild / engine swap / dump the car level. Which way is better, depends on your needs.

If it was me, even with oil consumption at moderate level - say 1 quart ever 3000 or so miles - I'd be looking at an engine rebuild or swap, as that consumption will only get worse with time.

If it was at levels of a quart ever 100-250 miles, which for me would be 2-4 quarts a week! That would be a near deal breaker - unless I was sentimentally attached to the car or that the engine, the car was in immaculate shape - I'd trade in the car and not bother to deal with it.

Biggest issue you'll likely run into is the replacement parts may NOT fix the oil consumption. Doing an engine swap, same concerns, as the replacement 2AZ-FE would have no guarantee to have no oil consumption issues down the road. You will have to verify that it uses the updated parts from the Toyota T-SB-0094-11 bulletin at the very minimum. Some have opted to go to a performance speed shop and have the work done there, as it is not usually done at most chain shops (they don't want to modify any part, from a liability standpoint).

Up to you. Without more information a piston soak from your mechanic may slow consumption, do nothing, or make it worse. If piston soak will permanently "fix" your oil consumption - at this point, no.

Keep it topped off with oil until you make a decision on what to do. Right now, likely looking at a rebuild, swap, or new engine - but keep in mind, it "may not" fix the problem. Much if happens to lie in the hands of the people doing the work. Could be a low cost, permanent fix or a money put of a nightmare.

Good example of successful fix is Bennie's corolla (on Toyotanation). He bought a very high mileage, heavy oil consuming 8th gen Corolla for cheap - ended up pulling the pistons, drilling holes and reassembling it without changing anything else - total cost less than $500. Was able to put on an amazing amount of mileage on it, without it ever consuming a drop of oil after the fix. He was able to do the work himself and save a bundle of money.

For an unlucky example, if you search this forum - look up posts from crypticlineage. He owned a 8th gen Corolla with excessive oil consumption. At the time, the options were very similar to your case - rebuild, swap engines, making sure it had updated pistons or just dump the car. As the car was otherwise mechanically sound and he just recently bought it - he opted for the safest bet of swapping in a early 9th gen 1ZZ-FE engine from a low mileage donor car (newer pistons, revised cam, better induction - ie, a good upgrade). Unfortunately, it unraveled into problems after problems, as the swap wasn't done correctly initially / had a bad engine the first time around.

Don't remember off the top of my head what he ended up doing, but he still had problems with the swap - might have finally dumped the car for something more reliable.

If the Camry is already paid off, because you can't see it every day, work on it easily - might be easier to cut your losses and dump the car while its resale value is still relatively high, at least from a point-of-mind standpoint. But the final decision is up to her / you.