Gduerson

Anyone had any success with additives that slow down or eliminates oil burning in the engine?

Oro

Check/replace the rear valve cover. Get one off a 2002+ model. It was the cause of many problems. Even if the internal baffles are not the problem, the rear valve cover gasket can leak a LOT of oil without you noticing.

How much oil is disappearing, are you sure it is being burned and not lost otherwise? What oil are you using?

Replace the pcv valve if you have not, and do not do the above rear cover change.

If the engine was abused, long oil change intervals, etc. and you suspect ring issues, run this oil:

https://www.valvolineglobal.com/en/restore-and-protect/

These engines are not oil burners on average. We still have two of these engines in the family (family being important to us, more on that below), neither use oil. One with 185k on it, the other 340k. No make-up oil in 7k intervals. What is the history of the car/engine?

I’m originally from Louisville. My favorite cousin just divorced one of the Hatfields. But if you are a McCoy or neutral, we will help you out.

Gduerson

since about 2000 I’ve been neutral.

Thanks for advice. I am not sure if the two suggested repairs have been done. Any tips on how I would be able to look at it and know?

salimshah

Add a catch can in the PCV line to the intake and that will tell you if your loss is from there. Indirect pointers are, sludge in the engine. This issue happens when the engine is higher than 2700 rpm [Cruising at high speed]. First gen engine was not for cruising at 75MPH. My unproven theory is that engine pump is pushing lot of oil up and the drain tubes are not dripping the oil down fast enough.

Salim

Gduerson

oh and also a question…. It may just be in my head but I’ve always been worried about additives or ring conditioners etc in an older car that is NOT leaking oil. It seems like this happened to me on an older Honda I had. Seemed like Used some engine cleaner product and it make it leave worse. Curious on your opinion of something like this valvoline oils would actually do anything to cause the engine to start leaking. Again that may just be in my head. 🤷🏼‍♂️

Oro

1) Tell me what happened in 1999.

2) Salim’s theory may not be bad; it’s an oiling issue I have in another vehicle. But against the theory, the 2002 valve cover change fixed the issue for the most part, so I think the drain capacity is in fact OK (just a guess, not saying he’s completely wrong).

3) He is 100% correct that adding a catch-can (it is cheap and easy) will help diagnose. The conventional wisdom on this is that the PCV valve allowed too much oil to be sucked out of the valve cover. The 2002+ mod baffled the area and blocked oil suction, reduced it to just gasses and minimal oil vapor. I think I have a pic of the area on my phone, I’ll check.

The PCV valve is on the forward end of the rear bank cover (near the shock tower on the passenger side). It is difficult but not impossible to change w/o removing intake assembly. I have this engine in an 02 ES and 05 RX, not identical to yours but I am assuming it’s mostly the same. The back bank is hard to access and gets neglected, and jammed into the firewall gets no air cooling - that is why the back bank tens to have more issues, and power steering issues on this car more than normal for lexus (it is under the engine against the firewall).

Still need to no more about what happened in 1999.

kgr75

I wondered about it too so I called the dealer and they said a quart every thousand miles was "normal"! So where's it going? It's not burning it, it's not leaking so where's it going? It's lost in the PCV system through oil vapor! Mine now has 200K on it and was throwing and erasing codes constantly. I knew it was a GDI engine which are prone to carbon up because of no fuel in the intake air. I removed the intakes and found massive carbon buildup. Attempted manual cleaning which was a joke so I went to the store and got some oven cleaner. I filled all the intake runners of the closed valves and let it sit overnight. In the morning I vacuumed the sludge out and finished cleaning with lacquer thinner. rotated the engine 360 degrees and repeated for the other 3. Looked in the cylinders and they were also terribly cartooned up too so I filled the cylinders with oven cleaner. let it sit overnight again and used lacquer thinner for the multiple cleanup cycles. Eventually got the cylinders cleaned up and reassembled. At first lots of smoke but after a couple minutes cleaned up and now it runs like a new car, I knew what I was doing was a bit risky but the prospect of a complete rebuild (which I could do) wasn't appealing to me so I took the calculated risk and it paid off big time!

Oro

That’s good work, but the 1MZ-fe engine is not GDI. What car are you talking about, just to check?

salimshah

When you ask dealership, they have a spec by manufacturer and they quote it back to you.

The spec simply means, that it the threshold for a defect and we know that is not an indicative of "normal".

Salim

Gduerson

Guys thanks a ton for this info. Not going to lie some of this is a bit over my head but I’m going to research it and monitor this new to me rx300 I just acquired and keep learning as I go. Thanks again.

mhay

I recently added a catch can to my 1998 Harrier (same vehicle basically) and it is surprising how much oil it collects. I had to empty it after about 1 month. I will soon need to empty it again.

salimshah

Are you using any modified oil .. such as high milage. Also what rpms do you see when you are cruising.

Salim

mhay

I use regular (non-synthetic) 10W30 oil. Nothing special. I don't even remember which brand I bought last time. I confirmed my PCV is working also. I will try the valve cover update if I can get one without too much hassle.

While cruising it is always in 4th gear, around 1500rpm or so. I mostly do city driving though. A lot of stop and go. 50 - 60 mph maximum.

This is the catch can I bought. Amazon stuff.

https://www.ievilenergy.com/collecti...atch-can-300ml

sktn77a

iTrader: (2)

They all say that. It's to protect themselves from having to replace engines under warranty. Of course, most of them know even less than you so they keep spouting that even after the engine is out of warranty!

It's not normal!