Oil consumption at 136k miles - too high

I actually haven't gotten any missfires, yet. I used to get the EGR Issues in the past until I cleaned out the cooler and then all went away. I think you might be right with your theory though. I know I am not getting great mileage anymore but I am guessing it might be just from my O2 sensors failing but not giving me a code, yet. On that note, I can completely see your theory being the root of our issues. I am burning more than 1quart every 1000 miles though. I am just shy of 200K and some times Ill check my oil and ill burn a quart is 400 miles while other times its closer to your burn. In Oct I plan on tearing the motor down and replacing rings and other items.

 

That will make an interesting report. Any bets whether you'll find the rings to be:
1)clogged with hard carbon (as some have theorized),
2)badly worn, or
3)perfectly fine?

 

I am going to guess badly worn and full of carbon. I am not expecting good results to be completely honest. Thankfully I have other vehicles that I can drive so I can take my time and tear it down and repair/fix what needs to be fixed. Hopefully I will be able to get to the root of my problem and have great results of normal mileage and no oil burn between oil changes and if there is, very very minimal.

 

Interesting!

 

Please keep me updated with your oil burn.

 

Perhaps EGR plumbing leading to the intake manifold would eventually "block off" itself via clogging. The manifold passages might still need to be cleared to avoid misfire due to unequal distribution of exhaust gas.

Let us know what effects you notice from this change. Fuel consumption may be a bit worse than normal. Oil consumption shouldn't change much.

When the EGR valve on my Mazda started leaking, I replaced it. When the vacuum amplifier for the EGR subsequently failed, at well past 300K miles, I gave up and shut off EGR exactly the same way you did. It ran another quarter-million miles (roughly) with no further EGR issues.

 

my personal theory is the opposite.

i posted a poll suggesting oil consumption is more common when people change oil at 10000 miles vs 5000: oil consumption vs length of oil change interval | PriusChat

a few prius engine teardown pictures posted here (sorry, don't have a link handy) showed coked oil deposits at the oil rings. this is a common theme in toyota engines with oil consumption.

but, why 0w20 full synthetic oil would fail and produce those deposits?

what if plugged EGR pipes put more stress on oil via oxidation and nitration?

note that if ring groove deposits develop, they are irreversible (and lead to accelerated ring wear), unless one does oil flush/piston soaks early on in the process.

 

Search here on Infineum to see some Camry Hybrid pics with messed up piston rings. Normally I say you might try Mobil-1 High Mileage but I am not sure there is a Mobil-1 High Mileage for Gen3 (5W-20 style). There is a 5W-30 version.

http://www.api.org/~/media/files/certification/engine-oil-diesel/forms/whats-new/9-dap-understanding-lubricant-requirements-of-hybrid-electric-vehicles-dclarke-infineum-usa.pdf

 

Makes me wonder how the Gen 2 is capable of meeting the PZEV emissions standard without EGR. Was EGR one of the ways Toyota increased the fuel economy of the Gen 3? Seems so. Not worth it considering the headaches it causes.

Another reason I'm glad I didn't buy a Gen 3 to replace my Gen 2.

MERGED

The DTC undoubtedly will be P0402 - EGR flow insufficient detected.

The main issue with living with a check engine light illuminated at all times is that you will need to scan for codes periodically to find out if any other ones have popped up. I wouldn't like that one bit.

 

what type/brand of oils have you used in your car? 5w20 probably means non-synthetic group3.

We have Gen3 with 180k and zero oil consumption. Only put Mobil 1 0w20 Advance in to it, 17 changes by now.

M1 may be not the best oil wear-wise, but out of widely available oils it produces least deposits when burned. I would also recommend to buy Top Tier gas only, since it has x3 detergents mandated by EPA.

The 0w20 full synthetic at least until recent time was Group 4. Which means higher flush point, and no deposits.

With respect to EGR and oil it is more of the chicken and egg question. You can't say one caused by another or vice versa; they go together.

I am with you on piston soak/oil flush, this can alleviate oil burn issue.

Another good prevention is to replace worn valve stem seals. It is a several hundred dollar job, but it can/will prolong engine life considerably.

The valve seals are weak point of OHC engines. Comparing to pushrod they have too much oil in the head, and when seals wear oil starts getting sucked in on intake cycle. Ignore it for 20-30k and oil rings will coke on oil rings. Then it will start burning 1qt per 1,000mi or so, and the only answer is rebuild.

 

overlapping of the valves. for reasons that are not clear to me, the 1.8 engine doesn't have VVT on the exhaust cam and can't overlap the valves, hence the conventional EGR valve and piping.

for the record, in USA, group 3 is considered "full synthetic."

how do you know this? any DIY testing?

good to know, is this M1 AFE?

in my experience with toyotas, valve seals are not the problem. the problem is pistons running hot (for max fuel efficiency and low emissions) combined with too little oil circulation in ring grooves, promoting oil deposits over time. saturn engines had the very same problem.

 

I cant speak for the Prius, however if you do the Smog Delete on a Yota 22RE motor, nothing negative happens, unless you have to go through emissions.

There should also be a test for the EGR to insure it is operating. Also Yota uses vacuum modulators in the Smog systems, if the VM isn't working, your EGR isn't working.

 

any pinging yet? EGR delete will result in hotter combustion chambers, and burned exhaust valves, not to mention NOx emissions.

 

Only since Mobil lost lawsuit ton Castrol in 1999. From what I've read Mobil makes AFE from G3/4 mix.

No I had seen it on one of the AMSoil sponsored tests. Another good ones were Redline, AMSoil(obvoiuosly) and I think Penzoil Ultra? or maybe it was Purple..

From what I spoke to engineer who tested oils back in 90s for BMW, they found Castrol to be the worse and Redline is the best. M1 was very good but that was when they were 100% PAO.

yes.

If this is the case piston ring soak should alleviate issue. I had replace valve seals on Mazda engine at 200k and that 1.5L went to 434k w/o rebuild. When we got seals out they looked like they were made out of plastic.I think they are using better seals now, and Prius runs engine at low manifold vacuum, so it should be lesser issue. But it is a weak point on most OHC/DOHC engines, so usually ring soak + valve seal could substitute rebuild if you caught it early enough.

 

Yeah, this is their first gen of Prius to implement EGR, maybe the problems are just starting to emerge?

 

I watched a vid on youtube about cleaning a prius EGR pipe, the pipe looked like it came off my 26 year old yota truck that sat for 10 years. absurd amount of sludge for such a new vehicle. So I went and pulled my oil cap, and yup, sludge! (haven't had it long enough to change oil, was Yota serviced up till i got it). One more thing to clean, sheesh.

friendly_jacek said: ↑
any pinging yet? EGR delete will result in hotter combustion chambers, and burned exhaust valves, not to mention NOx emissions.

I agree with Friendly_Jacek..... I dont know of a work around for the temps since the Prius timing cant be altered apparently, high NOx is unavoidable