wculbert

I have a 2006 IS350 that I bought new- currently has 175,000 miles on it. At about 140,000 it started using oil and has steadily gotten worse since then. I'm now at about a quart every 500-600 miles. My technician says this will continue to get worse and even suggested looking for another car. He says this is a known problem with the 250 and 350 engines.I love this car and have babied it for 15 years, so I hate to let it go. What experiences do any of you have? How much longer should I drive it?

Dealarr

If you go to factory technicians your oil consumption will keep getting worse. See if you can get someone to put in heavier oil or change it yourself. I am currently running 15W40 mineral oil to rough the walls and seat the rings of an IS250 through engine braking, doubt any owners would have driven their Lexus's hard in the beginning. It no longer burns oil with 173k's on the clock.

ncatona

I 2nd this by saying you should drive harder for an oil change interval either 3k if the oil darkens quickly or 5k and monitor it after each hard drive since you may burn more then. Hopefully it should clean things up for the low tension piston rings. I know for my 2006 with 135k miles it worked after doing some more consistent back to back redline runs to 40 or 60 for 15kmiles and also some manual mode shifting kept in the higher rpms once in a blue moon (of course I only did so when safe and not every time I drove the car either) and now I dont burn oil at all anymore and I only ran 5w30 pennzoil ultra platinum then platinum afterwards in it.... although any full "synthetic" 5w30 should do the trick with proper oil change intervals. My thread below or check my profile for it. Hopefully it should work for your 06 like it did mine, I originally thought driving slow (snow mode granny style under 2k rpms) for the first 10k miles after I got the car I thought it would stop any possible consumption but it didnt so I was like F it what do I have to loose, so I drove it more aggressively within the rpm range not the mph 🤣 and now 15k miles later.... im not loosing a drop of oil in a 5k oil change interval where before I lost over 1 quart.
https://www.clublexus.com/forums/is-2nd-gen-2006-2013/937758-is350-oil-consumption-dropped.html

Jeeves250

It might be something as simple as valve guides or seals; a cold start test, and a leakdown test would help you pinpoint it and see if you want to remedy the situation.

Gville350

iTrader: (10)

Was it clearly diagnosed as oil being burnt up in the CC or might have a leak been overlooked? Due to the amount of oil loss, probably would be an easy leak to spot, so less likely.

PCV valve, thicker oil, and perhaps a treatment of Seafoam to help free up any oil rings on your pistons that have been gummed up with carbon over time.

Jeeves250

That's a really good point; have a poke around up top and underneath to see if you can spot a leak. It's unlikely, but entirely possible!

AMIRZA786

I haven't redlined her very much, but I do try to take mine to at least 5K RPM at least once if I get a chance! It's definitely an engine that loves to be revved and not babied

2013FSport

iTrader: (2)

If mine blows up there will be little speculation as to why. It sees 6k weekly. Not daily but weekly. As long as they have good oil pressure AND are fully warmed up, all is well. It's certainly better than treating them like tractor engines! Plus the port velocity helps keep the top end clean.

If anyone is asking, I won't be subscribing to "thicker oil" being a fix. Cold starts are bad enough let alone, dry cold starts where the viscosity is too high to lubricate as it's intended too. JM2C

AMIRZA786

I doubt 6K will hurt anything, even if done daily with a properly warmed up engine. As I understand valve float doesn't start happening until after 7400 RPM.

As far as going to a thicker viscosity oil may not be a good idea as valves clearances were designed for 5W30, although the owners manual does mention "An oil with a higher viscosity may be better suited if the vehicle is operated at high speeds, or under extreme load conditions". My opinion on this is that this is applicable with using non synthetic dino oil, with a quality modern synthetic oil, 5W30 is plenty of protection even at high speeds

2013FSport

iTrader: (2)

Let's go with *all clearances... Oil technology is so much better than it was 25 years ago.

Mine has a tune so it's seen the likes of 7200+. The exhaust made it easy to bounce off the 7.2k limit as changed the curve enough that I didn't adapt fast enough...

Former significant other had to have this 69 Camero (327c.i.) and it fouled plugs as it passed so much blowby past the rings... none of the holes had the same compression. I drove it hard on when it was available and got out of needing plug swaps to a quart every 3k... That was before Ringfree and other chemicals.

AMIRZA786

The reason I specifically mentioned valve clearances was I was having an email discussion with an engineer from Mobile oil in 2018, and he told me that using oil with a higher viscosity than recommended by the manufacturer can interfere with valve timing (VVTi, VTC etc.).

Even bouncing off of 7200 rpm I think your fine. This is a fricken Toyota engine

ncatona

definitely! Its good to stretch out the legs once in awhile, I definitely dont beat on it like I used to since I stopped burning oil and plan on keeping it like that by taking good care of it and once in a blue moon a good redline run in automatic which cleans up gunk on the piston side and combustion chamber.

wculbert

Thanks for your comments NCA. “Drive it harder” is advice I look forward to trying! I’m going to try the Ringfree as well. Undecided about thicker oil.

wculbert

Thanks for your input FSport. Just ordered Ring Free and will definitely enjoy the higher RPMs. Undecided on the oil. Seldom gets very cold here in SC so I’m not too worried about cold starts.

ncatona

I would personally wait on the thicker oil, just try these previously stated methods first and then say after 10k miles you can decide then.