Hi there. I've a 2001 LS430 which is driving me crazy by slowly losing oil, it loses around 1 quart per month. I think I've replaced every seal that could've been replaced or anyone could think of. let me know if there is anything else that should be done
1.the rear crankshaft seal (which involved the removal of the transmission) - replaced.
2.valve cover gasket (including the spark-plug tube seals) - replaced.
3.pcv valve - replaced.
4.engine oil pan gasket - replaced.
5.engine oil level sensor gasket - replaced.
6. Left VVTI-Solenoid gasket (saw some old oil there, so why not?) - replaced.
maybe engine is burning oil? No smoke is coming out of my exhaust, even with the highest RPM revs.
maybe head gasket is blown? Engine oil & coolant both looks super clean. and I'm not losing any coolant.
maybe the camshaft seal? The timing belt is clean without any oily residue on it.
Car has 145,000 Miles, No CEL. And it drives completely fine. and it doesn't drip any oil on the garage floor.
I really love this car and don't wanna sell it. But this continuous oil decrement is driving me crazy.
Thanks in advance guys! and please excuse me If I made it complicated but I tried to be throughout as possible.

 

this will be my last resort. I'll have to use some dye after removing the belly pan.

 

What is condition of right and left bank ventilation (PCV) hoses?

After 20 years, valve stem seals may be tired.

Curious what oil you are using.

 

Are you getting any blue smoke?

 

Right hose was fine, While the left one was slightly cracked. I forgot to mention that I replaced that too along with some vacuum hoses that hardened

Oil is Total Quartz Fully Synthetic 5w30.


Not at all. even on high RPM's as mentioned.

 

How many miles per quart of oil are you losing?

 

Around every 500 miles I'm losing full quart, That's why I don't think it's something related to oil burning, Otherwise, at this rate it would've been producing blue clouds behind it.
I'll remove all the rear covers again tomorrow and steam clean the engine and re-check for leaks.

 

If it's not dripping on the ground, the engine is burning it. That kind of oil loss would be very obvious if it was an external leak. How do your spark plugs look? Oil soaked? Even with that high consumption rate you wouldn't see blue smoke from the exhaust.
Oil consumption of 1 quart in 1000 miles is considered "normal" by all manufacturers, some even more. Ford and Chevy have had these same problems for years and they are getting worse. Low-tension oil control rings improve mileage by reducing internal friction and that's all manufacturers care about. They don't pay for all the extra "normal" oil you must add.

 

^ I would suggest inspecting all 8 plugs. especially if you have completely eliminated external leakage with a dye test and removing the belly pan. It could be you have a ring problem in only 1 or 2 cylinders. FWIW, I don't think the LS430 has a reputation of an oil burner or leaker like these Chevy and Ford models. My '05 with 128K miles burns or leaks absolutely no oil in 5,000 miles, also running a 5W-30 synthetic.

 

Agreed. Our cars are not known to burn oil. Mine uses 0 oil in 6500 miles between oil changes. If you don't see significant oil dripping, it is most likely an internal issue.

 

Just taking wild guess but I think the dipstick has an o ring on it and it can leak oil. You probably already checked that. If you haven't already replaced the PVC valve do so. It is cheap insurance when having oil issues. There have been very few posts over the years concerning oil burning with LS430. Good luck.

 

Did you use an aftermarket PCV valve?

Two OEM style PCV valves used:
(2004-2006 LS430 dispensed with the PCV valve grommet in favor of screw in type PCV valve..)

 

Update guys! Today I removed the belly pan and drove randomly for like 2 hours then lifted the car on a hydraulic lift, everywhere was desert dry EXCEPT one point which was leaking generously!
The end of the oil dipstick tube was not properly attached to the engine till its end. I asked the mechanic to replace it and install it correctly all the way in.
Let's wait and see, But I'm optimistic this time, as I couldn't find any leak except this point.

Thank you so much guys for your help... I'll keep updating this post with the progress. at least I know that may Lex doesn't burn oil

 

There is an o-ring there that is probably leaking.



O-ring is item 11452B. Purchase from Lexus dealer.

 

Correct, that's the one I replaced today, maybe I incorrectly referred to it in my reply as a seal

​​​​​​​Thanks bud