IS 250 Direct injection - consequences - aah you know...

[SteveGee]

Hi all - sadly last year I had to fairly quickly find a car to replace my written off Ford Focus ST - (loved the handling of that car and the Turbo "kick"). So I was using my wife's car - and looking for a replacement with some style and looked to Lexus coz they're classy, V6, Toyota reliability and all the rest...

If I'd had more time to find one I would have bought an IS350; but there weren't any for sale at that point and my wife's transport situation for the new job was becoming urgent! I'm pretty happy withe the 250 and it moves pretty well - but I know the 350 is quicker still. But - there's the Direct Injection issue with the 250 and I know down the track (currenly has clocked only 105,000 kms) the intake and valves are going to grow carbon! 😝

I'm a young at heart 66 yr old - was thinking this might be my last car; so was fairly disappointed when I learned the IS250 had this issue - really kicking myself now! 🤪

Would love some opinion from the brains trust, would you:

1. Fit an Oil Catch Can - and just live with it?
2. Sell it and buy the 350?
3. Any other advice?
   
   Cheers
   
   Steve
    

[scudney]

How many 250's in the uk have you heard of that have had this issue? any?

[ColinBarber]

Can't comment on 2 - don't know the cost difference in your country (and we never had the 350 in the UK).

The carbon issue seems to be higher in the US, it is rare to see this issue in the UK that got to a stage where it impacted the running of the engine. Given the oil change interval in the US is less than the UK I can only assume it is related to people using poor quality oil in the US or there are emission differences with the engine. Do regular oil changes with fully synthetic oil and you shouldn't have too much of an issue. Certainly fit a catch can if you wish, it can only help.

If you needed to have the engine cleaned, that would still probably be cheaper than selling the 250, buying a 350 and paying for more fuel the 350 would consume over your ownership.

[MartinH]

More than 100,000 miles on my IS250, never any hint of this issue. Car is serviced with the specified oil and filled with E5 fuel.

[Linas.P]

It is kind of compound issue running car that is poorly serviced > causes oil burn  > causes poor lubrication > causes blow by > blow by increases pressure in crankcase > PCV blows oil vapour back into the intake > carbon/dust/oil combines to create carbon deposits on valves > overall this causes excessive wear/oil burning/more blow-by... and this cycle continues. Why we don't have it in UK... I really just can't explain, our service intervals are worse and many people pay very little attention to maintenance of any car overall, but we just don't get the issue here. 

So - really all comes down to regular service and good quality oil. Catch can does help, because it breaks the cycle, but realistically cycle should be stopped by regular oil changes and using good quality oil. 

IS350 does not have this issue, because it has port injectors which helps to dissolve build-up on intake valves. Same as Colin - I can't comment on whenever IS350 is right choice here, because I assume it will be more expensive and depending on local market it may or may bit be good deal. 

[SteveGee]

>>>IS350 does not have this issue, because it has port injectors which helps to dissolve build-up on intake valves.

Guys - this is a KNOWN issue on all petrol DI engines, not just IS250's. Manufacturers have been pushed harder and harder on emission targets and this tech does increases efficiency, yet causes this issue - just check all of the online articles (see just one below). Port + Direct injection as you mentioned has the added solvent action of fuel on the intakes, to eliminate it altogether.

My understanding - it's a very gradual deterioration; so will not be noticed unless you look inside the intakes and at valve stems and valves.

Cheers

Steve

 

[SteveGee]

18 hours ago, scudney said:

How many 250's in the uk have you heard of that have had this issue? any?

I'm in Australia - and was totally unaware myself until I saw some IS250 reviews here, where that was a complaint that was highlighted. Here's another Youtube article - 

 

[Linas.P]

No sure what you want here - do you want us just to provide you with justification to ditch IS250 and spend extra money on IS350? Are you looking for simple encouragement to upgrade... Sure go ahead, upgrade - IS350 is just much better car, with one of the best engines ever made and dream to drive, there are loads of reason to have IS350 if you budget allows it, but carbon build-up is just not one of those reasons.

As other have said - in UK we JUS DON'T have this issue. I don't know what exactly, but carbon build-up is simply not something UK or EU cars suffers from. I don't know if that is the driving we do, much lower mileage on average, better quality oils or what it is... but you will never hear that carbon build-up is what ended IS250 anywhere in Europe. 

Generally, this is compound issue of poor maintenance and extended service intervals. If you service your car say every 6 months/6000miles (I would recommend that on any car), then you unlikely to have issues with carbon build-up. Catch can is also good solution, but you basically need to do it on the new car right away, or do carbon cleaning (like walnut blasting) and then install catch-can. In short - catch can will not remove the carbon that is already there (also it is not really carbon, building... it is more like a sludge of oil vapor, carbon and dirt), it only slows down the build-up. 

All in all, this is sort of minor issue in grand schemes of things in IS250 ownership.

[scudney]

Sadly some people just  seem to be blinded by their own convictions real or unreal, at the end of the day do whatever suits you whatever that might be

[SteveGee]

On 11/12/2024 at 5:38 AM, scudney said:

Sadly some people just  seem to be blinded by their own convictions real or unreal, at the end of the day do whatever suits you whatever that might be

Yeah - I guess I must be blind then; or was genuinely concerned about the deterioration over time, of what is otherwise an awesome car.

Cheers

Steve